1. Foreword
. Preface
. Introduction to Sustainability: Humanity and the Environment
1. An Introduction to Sustainability: Humanity and the
Environment
. What is Sustainability?
. The IPAT Equation
. Human Consumption Patterns and the “Rebound” Effect
. Challenges for Sustainability
6. Chapter Review Questions
4. The Evolution of Environmental Policy in the United States
1. The Evolution of Environmental Policy in the United
States — Chapter Introduction
2. The American Conservation Movement
3. Environmental Risk Management
4. Sustainability and Public Policy
5. Public Health and Sustainability
5. Climate and Global Change
1. Climate and Global Change — Chapter Introduction
2. Climate Processes; External and Internal Controls
3. Milankovitch Cycles and the Climate of the Quaternary
4. Modern Climate Change
5. Climate Projections
6. Biosphere
1. Biosphere — Chapter Introduction
2. Biogeochemical Cycles and the Flow of Energy in the
Earth System
3. Biodiversity, Species Loss, and Ecosystem Function
4. Soil and Sustainability
7. Physical Resources: Water, Pollution, and Minerals
WwW N
wi BW N
1. Physical Resources: Water, Pollution, and Minerals -
Chapter Introduction
. Water Cycle and Fresh Water Supply
. Case Study: The Aral Sea - Going, Going, Gone
. Water Pollution
. Case Study: The Love Canal Disaster
. Mineral Resources: Formation, Mining, Environmental
Impact
7. Case Study: Gold: Worth its Weight?
8. Environmental and Resource Economics
1. Environmental and Resource Economics - Chapter
Introduction
. Tragedy of the Commons
. Case Study: Marine Fisheries
. Environmental Valuation
. Evaluating Projects and Policies
. Solutions: Property Rights, Regulations, and Incentive
Policies
9. Modern Environmental Management
1. Modern Environmental Management — Chapter
Introduction
2. Systems of Waste Management
3. Case Study: Electronic Waste and Extended Producer
Responsibility
4. Government and Laws on the Environment
5. Risk Assessment Methodology for Conventional and
Alternative Sustainability Options
10. Sustainable Energy Systems
1. Sustainable Energy Systems - Chapter Introduction
2. Environmental Challenges in Energy, Carbon Dioxide,
Air, Water and Land Use
3. Case Study: Greenhouse Gases and Climate Change
Au KRWN
AuBRWN
4. Energy Sources and Carriers
1. Electricity
1. Electricity
2. Fossil Fuels (Coal and Gas)
3. Nuclear Energy
4. Renewable Energy: Solar, Wind, Hydro and
Biomass
2. Liquid Fuels
1. Fossil Fuel (Oil)
2. The Conversion of Biomass into Biofuels
3. Heat
1. Geothermal Heating and Cooling
o. Energy Uses
1. Electric and Plug-in Hybrids
2. Combined Heat and Power
6. Applications of Phase Change Materials for Sustainable
Energy
11. Problem-Solving, Metrics, and Tools for Sustainability
1. Problem-Solving, Metrics, and Tools for Sustainability -
Chapter Introduction
2. Life Cycle Assessment
3. Derivative Life Cycle Concepts
1. Sustainability Metrics and Rating Systems
2. Footprinting: Carbon, Ecological and Water
3. Case Study: Comparing Greenhouse Gas Emissions,
Ecological Footprint and Sustainability Rating of a
University
4. Food Miles
. Environmental Performance Indicators
6. Case Study: UN Millennium Development Goals
Indicator
4. Sustainability and Business
U1
12. Sustainability: Ethics, Culture, and History
1
ie
8.
. The Human Dimensions of Sustainability: History,
Culture, Ethics
. It’s Not Easy Being Green: Anti-Environmental
Discourse, Behavior, and Ideology
. The Industrialization of Nature: A Modern History (1500
to the present)
. Sustainability Studies: A Systems Literacy Approach
. The Vulnerability of Industrialized Resource Systems:
Two Case Studies
. Case Study: Agriculture and the Global Bee Colony
Collapse
Case Study: Energy and the BP Oil Disaster
Sustainability Ethics
13. Sustainable Infrastructure
1.
. The Sustainable City
. Sustainability and Buildings
. Sustainable Energy Practices: Climate Action Planning
. Sustainable Transportation: Accessibility, Mobility, and
wm BW NN
NI OO
Sustainable Infrastructure - Chapter Introduction
Derived Demand
. Sustainable Stormwater Management
. Case Study: A Net-Zero Energy Home in Urbana, Illinois
Foreword
Sustainability is derived from two Latin words: sus which means up and
tenere which means to hold. In its modern form it is a concept born out of
the desire of humanity to continue to exist on planet Earth for a very long
time, perhaps the indefinite future. Sustainability is, hence, essentially and
almost literally about holding up human existence. Possibly, the most
succinct articulation of the issue can be found in the Report of the World
Commission on Environment and Development. The report entitled “Our
Common Future!!2™otel” primarily addressed the closely related issue of
Sustainable Development. The report, commonly know as the Brundtland
Report after the Commission Chair Gro Harlem Brundtland, stated that
“Humanity has the ability to make development sustainable to ensure that it
meets the needs of the present without compromising the ability of future
generations to meet their own needs.” Following the concept of Sustainable
Development, the commission went on to add ” Yet in the end, sustainable
development is not a fixed state of harmony, but rather a process of change
in which the exploitation of resources, the direction of investments, the
orientation of technological development, and institutional change are made
consistent with future as well as present needs. We do not pretend that the
process is easy or straightforward. Painful choices have to be made. Thus,
in the final analysis, sustainable development must rest on political will.”
Sustainability and the closely related concept of Sustainable Development
are, therefore, very human constructs whose objective is to insure the very
survival of humanity in a reasonably civilized mode of existence. Here,
however, I will focus primarily on Sustainability.
Report of the World Commission on Environment and Development: Our
Common Future. 1987. www.un-documents.net/wced-ocf.htm.
The seriousness of the issue of Sustainability has become increasingly
important and obvious over the last fifty years driven by an increasing
human population with increasing per capita resource consumption on a
planet which is after all finite. Note that the World population ome!
increased from approximately 2.5 billion in 1950 to about 7.0 billion in
2012. Furthermore, total World consumption expenditures! {omote] rose from
about 171 Billion in 1960 to approximately 44,000 billions in 2010
expressed in 2012 U.S. dollars. This is not to say that consumption is
necessarily bad, but rather that there are so many people consuming so
many resources that both the World environment and human consumption
will have to be managed with far more care and delicacy than has been
necessary in all of the historical past.
U.S. Census Bureau, 2012.
http://www.census.gov/population/international/data/idb/worldpoptotal.php.
World Bank, 2012. http://databank.worldbank.org/ddp/home.do?
Step=3&id=4.
A text such as the one being presented here is of paramount importance
because it will help to educate the next generation of students on the very
important subject of sustainability. Now sustainability is not exactly a
discipline such as, for example, physics. Rather it is truly a metadiscipline
drawing on nearly all of existing human knowledge in approximately equal
parts and with more or less equal importance. This is not to say that
different disciplines have not in the past drawn ideas from each other,
creating hybrid disciplines such as, for instance, biophysics - a fusion of
physics and biology. Rather, in Sustainability the range of ideas and issues
reach from the depth of biological sciences to the physical sciences and to
the social sciences, including politics. Additionally, the relative importance
of each of these aspects seems to be about the same. The reasons for this
inherent, perhaps unprecedented complexity, is that sustainability is about
sustaining human existence which requires many things to be sustained
including functioning economic, social, and political systems along with a
supportive physical and biological environment and more.
Hence, the effort to produce a text covering the breadth of sustainability
must by necessity come from a comprehensive group of specialists as is the
case here. This allows each field of study to bring its own unique
perspective and shed its own light on a very complex and important subject
which could otherwise be intractable. The authors very interestingly point
out in the preface that the text does not necessarily present a self-consistent
set of ideas. Rather, a degree of diversity is accepted within the overall
rubric of Sustainability and Science itself. This may be unusual for an
academic text, but it is necessary here. The reason is that environmental
problems of our time are both time-sensitive and evolving, and a complete
understanding does not exist and may never exist. But the issues still have
to be addressed in good faith, in a timely manner, with the best science on
hand. With the reader’s indulgence, I would like to draw an analogy to a
physician who has the responsibility of healing or attempting to heal
patients using the best available medical science in a timely manner,
knowing that a complete understanding of medical science does not exist
and, in fact, may never exist.
It is my sincerest hope this work shared freely and widely will be an
educational milestone as humanity struggles to understand and solve the
enormous environmental challenges of our time. Further, the text
“Sustainability: A comprehensive Foundation,” helps to provide the
intellectual foundation that will allow students to become the engines that
move and maintain society on the path of Sustainability and Sustainable
Development through the difficult process of change alluded to in “Our
Common Future.”
Heriberto Cabezas
Cincinnati, Ohio
March 2012
Preface
This text is designed to introduce the reader to the essential concepts of
sustainability. This subject is of vital importance — seeking as it does to
uncover the principles of the long-term welfare of all the peoples of the
planet — but is only peripherally served by existing college textbooks.
The content is intended to be useful for both a broad-based introductory
class on sustainability and as a useful supplement to specialist courses
which wish to review the sustainability dimensions of their areas of study.
By covering a wide range of topics with a uniformity of style, and by
including glossaries, review questions, case studies, and links to further
resources, the text has sufficient range to perform as the core resource for a
semester course. Students who cover the material in the book will be
conversant in the language and concepts of sustainability, and will be
equipped for further study in sustainable planning, policy, economics,
climate, ecology, infrastructure, and more.
Furthermore, the modular design allows individual chapters and sections to
be easily appropriated — without the purchase of a whole new text. This
allows educators to easily bring sustainability concepts, references, and case
studies into their area of study.
This appropriation works particularly well as the text is free —
downloadable to anyone who wishes to use it. Furthermore, readers are
encouraged to work with the text. Provided there is attribution to the source,
users can adapt, add to, revise and republish the text to meet their own
needs.
Because sustainability is a cross-disciplinary field of study, producing this
text has required the bringing together over twenty experts from a variety of
fields. This enables us to cover all of the foundational components of
sustainability: understanding our motivations requires the humanities,
measuring the challenges of sustainability requires knowledge of the
sciences (both natural and social), and building solutions requires technical
insight into systems (such as provided by engineering, planning, and
management).
Readers accustomed to textbooks that present material in a unitary voice
might be surprised to find in this one statements that do not always agree.
Here, for example, cautious claims about climate change stand beside
Sweeping pronouncements predicting future social upheaval engendered by
a warming world. And a chapter that includes market-based solutions to
environmental problems coexists with others that call for increased
government control. Such diversity of thought characterizes many of the
fields of inquiry represented in the book; by including it, we invite users to
engage in the sort of critical thinking a serious study of sustainability
requires.
It is our sincerest hope that this work is shared freely and widely, as we all
struggle to understand and solve the enormous environmental challenges of
our time.
An Introduction to Sustainability: Humanity and the Environment
Learning Objectives
After reading this chapter, students should be able to
e learn the meaning of sustainability in its modern context
e acquire a basic facility for using the IPAT equation
e learn about patterns of human consumption
e understand the major factors that contribute to unsustainable impacts
What is Sustainability?
In 1983 the United Nations General Assembly passed resolution 38/161
entitled “Process of Preparation of the Environmental Perspective to the
Year 2000 and Beyond,” establishing a special commission whose charge
was:
a. To propose long-term environmental strategies for achieving
sustainable development to the year 2000 and beyond;
b. To recommend ways in which concern for the environment may be
translated into greater co-operation among developing countries and
between countries at different stages of economic and social
development and lead to the achievement of common and mutually
supportive objectives which take account of the interrelationships
between people, resources, environment and development;
c. To consider ways and means by which the international community
can deal more effectively with environmental concerns, in the light of
the other recommendations in its report;
d. To help to define shared perceptions of long-term environmental issues
and of the appropriate efforts needed to deal successfully with the
problems of protecting and enhancing the environment, a long-term
agenda for action during the coming decades, and aspirational goals
for the world community, taking into account the relevant resolutions
of the session of a special character of the Governing Council in 1982.
The commission later adopted the formal name “World Commission on
Environment and Development” (WCED) but became widely known by the
name of its chair Gro Harlem Brundtland, a medical doctor and public
health advocate who had served as Norway’s Minister for Environmental
Affairs and subsequently held the post of Prime Minister during three
periods. The commission had twenty-one members drawn from across the
globe, half representing developing nations. In addition to its fact-finding
activities on the state of the global environment, the commission held
fifteen meetings in various cities around the world seeking firsthand
experiences on the how humans interact with the environment. The
Brundtland Commission issued its final report “Our Common Future” in
1987.
Although the Brundtland Report did not technically invent the term
“sustainability,” it was the first credible and widely-disseminated study that
probed its meaning in the context of the global impacts of humans on the
environment. Its main and often quoted definition refers to sustainable
development as “...development that meets the needs of the present
without compromising the ability of future generations to meet their own
needs.” The report uses the terms “sustainable development,” “sustainable,”
and “sustainability” interchangeably, emphasizing the connections among
social equity, economic productivity, and environmental quality. The
pathways for integration of these may differ nation by nation; still these
pathways must share certain common traits: “the essential needs of the
world's poor, to which overriding priority should be given, and the idea of
limitations imposed by the state of technology and social organization on
the environment's ability to meet present and future needs.”
Thus there are three dimensions that sustainability seeks to integrate:
economic, environmental, and social (including sociopolitical). Economic
interests define the framework for making decisions, the flow of financial
capital, and the facilitation of commerce, including the knowledge, skills,
competences and other attributes embodied in individuals that are relevant
to economic activity. Environmental aspects recognize the diversity and
interdependence within living systems, the goods and services produced by
the world’s ecosystems, and the impacts of human wastes. Socio-political
refers to interactions between institutions/firms and people, functions
expressive of human values, aspirations and well-being, ethical issues, and
decision-making that depends upon collective action. The report sees these
three elements as part of a highly integrated and cohesively interacting, if
perhaps poorly understood, system.
The Brundtland Report makes it clear that while sustainable development is
enabled by technological advances and economic viability, it is first and
foremost a social construct that seeks to improve the quality of life for the
world’s peoples: physically, through the equitable supply of human and
ecological goods and services; aspirationally, through making available the
widespread means for advancement through access to education, systems of
justice, and healthcare; and strategically, through safeguarding the interests
of generations to come. In this sense sustainability sits among a series of
human social movements that have occurred throughout history: human
rights, racial equality, gender equity, labor relations, and conservation, to
name a few.
Overlapping Themes of the Sustainability
Paradigm A depiction of the sustainability
paradigm in terms of its three main components,
showing various intersections among them.
Source: International Union for the
Conservation of Nature
The intersection of social and economic elements can form the basis of
social equity. In the sense of enlightened management, "viability" is formed
through consideration of economic and environmental interests. Between
environment and social elements lies “bearability,” the recognition that the
functioning of societies is dependent on environmental resources and
services. At the intersection of all three of these lies sustainability.
The US Environmental Protection Agency (US EPA) takes the extra step of
drawing a distinction between sustainability and sustainable development,
the former encompassing ideas, aspirations and values that inspire public
and private organizations to become better stewards of the environment and
that promote positive economic growth and social objectives, the latter
implying that environmental protection does not preclude economic
development and that economic development must be ecologically viable
now and in the long run.
The Chapter The Evolution of Environmental Policy in the United
States presents information on how the three components that comprise
sustainability have influenced the evolution of environmental public policy.
greater detail the ethical basis for sustainability and its cultural and
historical significance.
Glossary
sustainable development
Development that meets the needs of the present without
compromising the ability of future generations to meet their own
needs.
The IPAT Equation
As attractive as the concept of sustainability may be as a means of framing
our thoughts and goals, its definition is rather broad and difficult to work
with when confronted with choices among specific courses of action. The
Chapter Problem-Solving, Metrics, and Tools for Sustainability is
devoted to various ways of measuring progress toward achieving
sustainable goals, but here we introduce one general way to begin to apply
sustainability concepts: the IPAT equation.
As is the case for any equation, IPAT expresses a balance among interacting
factors. It can be stated as
Equation:
I=PxAxT
where I represents the impacts of a given course of action on the
environment, P is the relevant human population for the problem at hand, A
is the level of consumption per person, and T is impact per unit of
consumption. Impact per unit of consumption is a general term for
technology, interpreted in its broadest sense as any human-created
invention, system, or organization that serves to either worsen or uncouple
consumption from impact. The equation is not meant to be mathematically
rigorous; rather it provides a way of organizing information for a “first-
order” analysis.
Suppose we wish to project future needs for maintaining global
environmental quality at present day levels for the mid-twenty-first century.
For this we need to have some projection of human population (P) and an
idea of rates of growth in consumption (A).
World Population: 1950-2050
os
Population (billions)
OFNWA TAN OOO
World Population Growth Source: U.S.
Census Bureau, International Data Base,
December 2010 Update
Figure World Population Growth suggests that global population in 2050
will grow from the current 6.8 billion to about 9.2 billion, an increase of
35%. Global GDP (Gross Domestic Product, one measure of consumption)
varies from year to year but, using Figure Worldwide Growth of Gross
Domestic Product as a guide, an annual growth rate of about 3.5% seems
historically accurate (growth at 3.5%, when compounded for forty years,
means that the global economy will be four times as large at mid-century as
today).
Real 2
Growth
Rate
(%) 0
-4
1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010
Year
Worldwide Growth of Gross Domestic Product Source: CIA World
Factbook, Graph from IndexMundi
Thus if we wish to maintain environmental impacts (1) at their current
levels (i.e. Ino59 = In919), then
Equation:
P2019 X Azoio X T2010 = P2050 < Azos0 X T2050
or
Equation:
Toso _ Poono0 ¥ Aw _ 1 5 1 _ ft
T5010 P2950 A250 1.35 4 5.4
This means that just to maintain current environmental quality in the face of
growing population and levels of affluence, our technological decoupling
will need to reduce impacts by about a factor of five. So, for instance, many
recently adopted “climate action plans” for local regions and municipalities,
such as the Chicago Climate Action Plan, typically call for a reduction in
greenhouse gas emissions (admittedly just one impact measure) of eighty
percent by mid-century. The means to achieve such reductions, or even
whether or not they are necessary, are matters of intense debate; where one
group sees expensive remedies with little demonstrable return, another sees
opportunities for investment in new technologies, businesses, and
employment sectors, with collateral improvements in global and national
well-being.
Human Consumption Patterns and the “Rebound” Effect
In 1865 William Jevons (1835-1882), a British economist, wrote a book entitled “The Coal
Question,” in which he presented data on the depletion of coal reserves yet, seemingly
paradoxically, an increase in the consumption of coal in England throughout most of the 19"
century. He theorized that significant improvements in the efficiency of the steam engine had
increased the utility of energy from coal and, in effect, lowered the price of energy, thereby
increasing consumption. This is known as the Jevons paradox, the principle that as technological
progress increases the efficiency of resource utilization, consumption of that resource will increase.
Increased consumption that negates part of the efficiency gains is referred to as “rebound,” while
overconsumption is called “backfire.” Such a counter-intuitive theory has not been met with
universal acceptance, even among economists (see, for example, “The Efficiency Dilemma”).
Many environmentalists, who see improvements in efficiency as a cornerstone of sustainability,
openly question the validity of this theory. After all, is it sensible to suggest that we not improve
technological efficiency?
Whether or not the paradox is correct, the fact that it has been postulated gives us pause to examine
in somewhat greater depth consumption patterns of society. If we let Q be the quantity of goods and
services delivered (within a given time period) to people, and R be the quantity of resources
consumed in order to deliver those goods and services, then the IPAT equation can be rewritten in a
slightly different way as:
Equation:
_ GDP Q es I
| P |» Fea «|B * |
R
where 13 represents the “resource intensity,” and [4] is the impact created per unit of resources
consumed. Rearranging this version of the equation gives:
Equation:
ro-(f
which says simply that resources consumed are equal to the quantity of goods and services
Q
R
use efficiency, also known as “resource productivity” or “eco-efficiency,” an approach that seeks to
minimize environmental impacts by maximizing material and energy efficiencies of production.
Thus we can say:
Equation:
delivered times the resource intensity. The inverse of resource intensity is called the resource
Eco — efficiency
R=Q*x foray |
that is, resources consumed are equal to goods and services delivered divided by eco-efficiency.
Whether or not gains in eco-efficiency yield genuine savings in resources and lower environmental
impacts depends on how much, over time, society consumes of a given product or service (i.e. the
relative efficiency gain, a) must outpace the quantity of goods and services delivered a . In the
terms of Jevons paradox, if af = ac then the system is experiencing “backfire.”
Part of the problem in analyzing data pertaining to whether or not such “overconsumption” is
happening depends on the specific good or service in question, the degree to which the data truly
represent that good or service, and the level of detail that the data measure. Table Historical
Efficiency and Consumption Trends in the United States summarizes some recent findings from
the literature on the comparative efficiency and consumption for several activities over extended
periods of observation. Taken collectively these activities capture several basic enabling aspects of
modern society: major materials, transportation, energy generation, and food production. In all
cases the data oe that over the long term, consumption outpaces gains in efficiency by wide
margins, (i.e., woe = Ae), It should also be noted that in all cases, the increases in consumption
are significantly greater than increases in population. The data of Table Historical Efficiency and
Consumption Trends in the United States do not verify Jevons paradox; we would need to know
something about the prices of these goods and services over time, and examine the degree to which
substitution might have occurred (for instance aluminum for iron, air travel for automobile travel).
To see if such large increases in consumption have translated into comparable decreases in
environmental quality, or declines in social equity, other information must be examined. Despite
this, the information presented does show a series of patterns that broadly reflect human
consumption of goods and services that we consider essential for modern living and for which
efficiency gains have not kept pace; in a world of finite resources such consumption patterns
cannot continue indefinitely.
Avg Annual Avg Annual
Efficiency Increase in
Time Improvement Consumption Ratio:
Activity Period (%) (%) Consumption/Efficiency
; 1800-
Pig Iron 1990 14 4.1 3.0
: 1900-
Aluminum 2005 12 9.8 AS
a 1920-
Fertilizer 2000 1.0 8.8 8.9
Electricity- 1920- 13 5.7 45
Coal 2007
Activity
Electricity-
Oil
Electricity-
Nat Gas
Freight
Rail Travel
Air
Passenger
Travel
Motor
Vehicle
Travel
Time
Period
1920-
2007
1920-
2007
1960-
2006
1960-
2007
1940-
2006
Avg Annual
Efficiency
Improvement
(%)
15
0.3
Avg Annual
Increase in
Consumption
(%)
Oc
9.6
2.0
6.3
3.8
Ratio:
Consumption/Efficiency
4.2
5.5
12
4.9
11.0
Historical Efficiency and Consumption Trends in the United States Source: Dahmus and
Gutowski, 2011
Our consumption of goods and services creates a viable economy, and also reflects our social
needs. For example, most of us consider it a social good that we can travel large distances rather
quickly, safely, and more or less whenever we feel the need. Similarly, we realize social value in
having aluminum (lightweight, strong, and ductile) available, in spite of its energy costs, because it
makes so many conveniences, from air travel to beverage cans, possible. This is at the center of the
sustainability paradigm: human behavior is a social and ethical phenomenon, not a technological
one. Whether or not we must “overconsume” to realize social benefits is at the core of sustainable
solutions to problems.
Resources
For more information about eco-efficiency, see the World Business Council for Sustainable
Development report titled "Eco-Efficiency: Creating more value with less impact"
References
Dahmus, J. B., and T. G. Gutowski (2011) “Can Efficiency Improvements Reduce Resource
Consumption? A Historical Analysis of Ten Activities” Journal of Industrial Ecology (accepted for
publication).
Glossary
eco-efficiency
An approach that seeks to minimize environmental impacts by maximizing material and
energy efficiencies of production.
Jevons paradox
The principle that as technological progress increases the efficiency of resource utilization,
consumption of that resource will increase.
overconsumption
A long-term result in which the increase in consumption is greater than the efficiency
improvement
Challenges for Sustainability
The concept of sustainability has engendered broad support from almost all
quarters. In a relatively succinct way it expresses the basis upon which
human existence and the quality of human life depend: responsible behavior
directed toward the wise and efficient use of natural and human resources.
Such a broad concept invites a complex set of meanings that can be used to
support divergent courses of action. Even within the Brundtland Report a
dichotomy exists: alarm over environmental degradation that typically
results from economic growth, yet seeing economic growth as the main
pathway for alleviating wealth disparities.
The three main elements of the sustainability paradigm are usually thought
of as equally important, and within which tradeoffs are possible as courses
of action are charted. For example, in some instances it may be deemed
necessary to degrade a particular ecosystem in order to facilitate commerce,
or food production, or housing. In reality, however, the extent to which
tradeoffs can be made before irreversible damage results is not always
known, and in any case there are definite limits on how much substitution
among the three elements is wise (to date, humans have treated economic
development as the dominant one of the three). This has led to the notion of
strong sustainability, where tradeoffs among natural, human, and social
capital are not allowed or are very restricted, and weak sustainability,
where tradeoffs are unrestricted or have few limits. Whether or not one
follows the strong or weak form of sustainability, it is important to
understand that while economic and social systems are human creations, the
environment is not. Rather, a functioning environment underpins both
society and the economy.
This inevitably leads to the problem of metrics: what should be measured
and how should the values obtained be interpreted, in light of the broad
goals of the sustainability paradigm? The Chapter Problem-Solving,
Metrics, and Tools for Sustainability addresses this in detail, but
presented here is a brief summary of the findings of the Millennium
Ecosystem Assessment (MEA), a project undertaken by over a thousand
internationally recognized experts, from 2001-2005, who assessed the state
of the world’s major ecosystems and the consequences for humans as a
result of human-induced changes. In its simplest form, a system is a
collection of parts that function together. The MEA presents findings as
assessments of ecosystems and ecosystem services: provisioning services
such as food and water; regulating services such as flood control, drought,
and disease; supporting services such as soil formation and nutrient cycling;
and cultural services such as recreational, spiritual, religious and other
nonmaterial benefits. MEA presents three overarching conclusions:
"Approximately 60% (15 out of 24) of the ecosystem services examined are
being degraded or used unsustainably, including fresh water, capture
fisheries, air and water purification, and the regulation of regional and local
climate, natural hazards, and pests. The full costs of the loss and
degradation of these ecosystem services are difficult to measure, but the
available evidence demonstrates that they are substantial and growing.
Many ecosystem services have been degraded as a consequence of actions
taken to increase the supply of other services, such as food. These trade-offs
often shift the costs of degradation from one group of people to another or
defer costs to future generations." "There is established but incomplete
evidence that changes being made are increasing the likelihood of nonlinear
changes in ecosystems (including accelerating, abrupt, and potentially
irreversible changes) that have important consequences for human well-
being. Examples of such changes include disease emergence, abrupt
alterations in water quality, the creation of “dead zones” in coastal waters,
the collapse of fisheries, and shifts in regional climate." "The harmful
effects of the degradation of ecosystem services are being borne
disproportionately by the poor, are contributing to growing inequities and
disparities across groups of people, and are sometimes the principal factor
causing poverty and social conflict. This is not to say that ecosystem
changes such as increased food production have not also helped to lift many
people out of poverty or hunger, but these changes have harmed other
individuals and communities, and their plight has been largely overlooked.
In all regions, and particularly in sub-Saharan Africa, the condition and
management of ecosystem services is a dominant factor influencing
prospects for reducing poverty."
Organizations such as the World Commission on Environment and
Development, the Millennium Ecosystem Assessment, and several others
including the Intergovernmental Panel on Climate Change, the Organization
for Economic Cooperation and Development, and the National Academy.
Report to Congress have all issued reports on various aspects of the state of
society and the environment. The members of these groups are among the
best experts available to assess the complex problems facing human society
in the 21° century, and all have reached a similar conclusion: absent the
enactment of new policies and practices that confront the global issues of
economic disparities, environmental degradation, and social inequality, the
future needs of humanity and the attainment of our aspirations and goals are
not assured.
Glossary
ecosystems
Dynamic systems of human, plant, animal, and microorganism
communities and the nonliving environment that interact as a
functional unit
ecosystem services
The benefits humans receive from ecosystems
strong sustainability
All forms of capital must be maintained intact independent of one
another. The implicit assumption is that different forms of capital are
mainly complementary; that is, all forms are generally necessary for
any form to be of value. Produced capital used in harvesting and
processing timber, for example, is of no value in the absence of stocks
of timber to harvest. Only by maintaining both natural and produced
capital stocks intact can non-declining income be assured.
weak sustainability
All forms of capital are more or less substitutes for one another; no
regard has to be given to the composition of the stock of capital. Weak
sustainability allows for the depletion or degradation of natural
resources, so long as such depletion is offset by increases in the stocks
of other forms of capital (for example, by investing royalties from
depleting mineral reserves in factories).
Chapter Review Questions
Exercise:
Problem:
What are the essential aspects of “sustainability” as defined in the
Brundtland Report?
Exercise:
Problem:
Define “strong” and “weak” sustainability and give examples of each.
Exercise:
Problem:
State, in your own words, the meaning of the “IPAT” equation?
Exercise:
Problem:
What is the “rebound” effect and how is it related to human patterns of
consumption?
The Evolution of Environmental Policy in the United States — Chapter
Introduction
In this module, the Chapter The Evolution of Environmental Policy in the
United States is introduced.
Introduction
It is not uncommon to think of the sustainability paradigm as being a recent
interpretation of environmental policy, one that was given credence by the
United Nations report "Our Common Future" (the Brundtland Report) when
it was first presented in 1987. Certainly the period during the final decade
of the twentieth century was witness to significant growth in our
understanding of the complexity and global reach of many environmental
problems and issues, and as discussed in Chapter An Introduction to
Sustainability; Humanity and the Environment, the Brundtland report
gave a Clear voice to these concerns through its analysis of human
dependency and quality of life on ecological systems, social networks, and
economic viability—systems that are closely intertwined and that require
more integrated approaches to solving the many problems that confront
humanity at this time. It is also true that it was among the first widely
disseminated writings to define and use the modern meaning of the term
"sustainable" through the often-quoted concept of "sustainable
development." However, it would be a mistake to conclude that
sustainability as a mental construct and policy framework for envisioning
the relationship of humans and nature came into being suddenly and at a
single moment in time. Most environmental historians who have studied
U.S. policy have discerned at least three distinct periods during which new
concepts and ideas, scientific understandings, technological advances,
political institutions, and laws and regulations came or were brought into
being in order to understand and manage human impacts on the
environment. These were (1) the American conservation movement, (2) the
rise of environmental risk management as a basis for policy, and (3) the
integration of social and economic factors to create what we now refer to as
the sustainability paradigm. In this chapter we will explore the roots of
modern sustainability (Module The American Conservation Movement),
see how our thinking about the environment has shifted (Module
Environmental Risk Management), and examine the ways that our
environmental public policies have changed through time (Module
Sustainability and Public Policy). Along the way it is important to
understand that this has been an evolutionary process and that these
environmental "eras," while reflecting the norms, attitudes, and needs of the
day, are still very much embodied within the modern concept of
sustainability.
The American Conservation Movement
In this module, the history of environmental policy in the United States and
the role of different groups in shaping environmental policy is discussed.
Learning Objectives
After reading this module, students should be able to
¢ understand the history of environmental policy in the United States
and the role of different groups in shaping environmental policy
Introduction
To most early colonists who immigrated to North America, for whom the
concept of “wastage” had no specific meaning, the continent was a land of
unimaginably vast resources in which little effort was made to treat,
minimize, or otherwise manage. This is not surprising, when one stand of
trees was consumed for housing or fuel, another was nearby; when one field
was eroded to the point of limited fertility, expansion further inland was
relatively simple; when rivers became silted so that fisheries were impaired,
one moved further upstream; and when confronted with endless herds of
wild animals, it was inconceivable that one might over-consume to the point
of extinction. European-settled America was a largely agrarian society and,
apart from the need to keep spaces productive and clear of debris, there was
little incentive to spend time and energy managing discharges to the
“commons” (see Module The Tragedy of the Commons). These attitudes
persisted well into the 19" century and aspects of them are still active in the
present day. While such practices could hardly be said to constitute an
“environmental policy,” they did serve the purpose of constellating a
number of groups into rethinking the way we went about managing various
aspects of our lives, in particular our relationship to the land and the
resources it contained or provided. As early as the mid-18" century, Jared
Eliot (1685-1763) of Connecticut, a minister, doctor, and farmer, wrote a
series of treatises on the need for better farming methods. He summarized:
"When our fore-Fathers settled here, they entered a Land which probably
never had been Ploughed since the Creation, the Land being new they
depended upon the natural Fertility of the Ground, which served their
purpose very well, and when they had worn out one piece they cleared
another, without any concer to amend their Land...(Carman, Tugwell, &
True, 1934, p. 29)."
Although Eliot avidly instructed his fellow farmers on better methods of
“field husbandry,” there is little evidence that his writings had a lasting
effect (he is most known for advances in the design of the “drill plough,” an
early planter that produced even rows of crops, increasing yields).
By 1850, the population of the United States was approaching 25 million
and increasing at the rate of three to four percent per year (for comparison
the population of England was about 26 million, of France 36 million, and
Germany about 40 million). Although the westward migration across North
America was well underway, most people still lived within a relatively
narrow strip of land along the east coast. By modern measures the United
States was not densely populated, and yet the perception of the country as
“big” and on the international stage was in contrast to the mentality just a
few decades before of a new world that had broken with the old, one of
endless open spaces and inexhaustible resources. The country was also
becoming more urbanized (about 15 percent of the population lived in
cities, three times the proportion of just fifty years before), and increasingly
literate.
Thus by the mid-19" century the American public was prepared to listen to
the messages of various groups who had become concerned about the
impacts of growth on society. Three groups in particular, of considerably
different sympathies and character, came to have profound influences on the
way we thought of ourselves in relation to the environment, on our land use
policies, and on providing environmental goods and services to the growing
population: the “resource efficiency” group, the transcendentalist
movement, and organized industrial interests.
Resource Efficiency
As typified by the concerns of Jared Eliot nearly a century before, there
were always some who were alarmed at widespread agricultural practices
that were wasteful, inefficient and, using the modern terminology,
unsustainable. By the early 1800s the cumulative impacts of soil erosion
and infertility, decreasing crop yields, and natural barriers to expansion
such as terrain and poor transportation to markets led to an organized effort
to understand the causes of these problems, invent and experiment with
new, more soil-conserving and less wasteful practices, communicate what
was being learned to the public, and begin to build government institutions
to promote better stewardship of the land and its resources. Although initial
conservation concerns were associated with farming, the same approach
soon found its way into the management of forests and timbering, wastes
from mining and smelting, and by the end of the century the control of
human disease outbreaks (most commonly associated with cholera and
typhoid) and the impact of chemical exposure on workers. There were
many individuals who contributed to understanding the scientific
underpinnings of the environment and educating practitioners: Eugene
Hilgard (agricultural science), John Wesley Powell (water rights), George
Perkins Marsh (ecological science), Franklin Hough and Gifford Pinchot
(sustainable forestry), J. Sterling Morton (forestry and environmental
education; co-founder of Arbor Day), Frederick Law Olmsted (landscape
architecture), and Alice Hamilton (industrial hygiene), to name a few. These
resource conservationists were instrumental in applying scientific methods
to solving the problems of the day, problems that were rooted in our
behavior toward the environment, and that had serious consequences for the
well-being of people. It was as a result of these efforts that the basis for the
fields of environmental science and engineering, agronomy and agricultural
engineering, and public health was established. Over time these fields have
grown in depth and breadth, and have led to the establishment of new areas
of inquiry.
Just as importantly, several federal institutions were created to oversee the
implementation of reforms and manage the government’s large land
holdings. Legislation forming the Departments of the Interior (1849), and
Agriculture (1862), the U.S. Forest Service (1881), the Geological Survey
(1879), and the National Park Service (1916) were all enacted during this
period. It was also the time when several major conservation societies, still
active today, came into being: the Audubon Society (1886), the Sierra Club
(1892), and the National Wildlife Federation (1935). Arbor Day was first
celebrated in 1872, and Bird Day in 1894.
The Transcendental Movement
It is beyond the scope of this text to analyze in great depth the basis of the
transcendental movement in America. It arose in the 1830s in reaction to
the general state of culture and society, increasing urbanism, and the rigidity
of organized religions of the time. It professed a way of thinking in which
the individual’s unique relationship to their surroundings was valued over
conformity and unreflective habits of living. But however philosophical its
aims and ethereal its goals, transcendentalism had a profound connection to
the natural environment; indeed, it is difficult to understand without
reference to human-environmental interactions and a re-envisioning of the
social contract of humanity with nature. Such were conditions at the time
that transcendentalism resonated with an increasingly literate society, and
became a major force in the further development of conservation as an
accepted part of the American experience.
The acknowledged leader of the transcendental movement was Ralph
Waldo Emerson (1803-1882). In his seminal essay Nature (1836), Emerson
sets the tone for a new way of envisioning our relation to the natural world:
To speak truly, few adult persons can see nature. Most persons do not see
the sun. At least they have a very superficial seeing. The sun illuminates
only the eye of the man, but shines into the eye and the heart of the child.
The lover of nature is he whose inward and outward senses are still truly
adjusted to each other; who has retained the spirit of infancy even into the
era of manhood. His intercourse with heaven and earth, becomes part of his
daily food. In the presence of nature, a wild delight runs through the man, in
spite of real sorrows. Nature says, -- he is my creature, and maugre all his
impertinent griefs, he shall be glad with me. Not the sun or the summer
alone, but every hour and season yields its tribute of delight; for every hour
and change corresponds to and authorizes a different state of the mind, from
breathless noon to grimmest midnight. Nature is a setting that fits equally
well a comic or a mourning piece. In good health, the air is a cordial of
incredible virtue. Crossing a bare common, in snow puddles, at twilight,
under a clouded sky, without having in my thoughts any occurrence of
special good fortune, I have enjoyed a perfect exhilaration. I am glad to the
brink of fear. In the woods too, a man casts off his years, as the snake his
slough, and at what period so ever of life, is always a child. In the woods, is
perpetual youth. Within these plantations of God, a decorum and sanctity
reign, a perennial festival is dressed, and the guest sees not how he should
tire of them in a thousand years. In the woods, we return to reason and faith.
There I feel that nothing can befall me in life, -- no disgrace, no calamity,
(leaving me my eyes,) which nature cannot repair. Standing on the bare
ground, -- my head bathed by the blithe air, and uplifted into infinite space,
-- all mean egotism vanishes. I become a transparent eye-ball; I am nothing;
I see all; the currents of the Universal Being circulate through me; I am part
or particle of God. The name of the nearest friend sounds then foreign and
accidental: to be brothers, to be acquaintances, -- master or servant, is then
a trifle and a disturbance. I am the lover of uncontained and immortal
beauty. In the wilderness, I find something more dear and connate than in
streets or villages. In the tranquil landscape, and especially in the distant
line of the horizon, man beholds somewhat as beautiful as his own nature.
(Emerson, 1836).
Here Emerson makes clear that his connection to the “Universal Being” is
made possible through communion with Nature, a creation so much greater
than he that he sees his physical reality as “nothing,” but his true nature (i.e.
his soul) becomes visible in the “tranquil landscape,” and the “distant line
of the horizon.” Such metaphorical language was and remains a powerful
reminder that our existence is dependent on the natural world, and that we
mismanage the environment at our peril.
Kindred Spirits. The painting, dated 1849,
depicts the artist, Thomas Cole, and poet,
William Cullen Bryant. Source: Asher Brown
Durand via Wikimedia Commons
Yet, it is difficult to fully appreciate Emerson’s vision of humans and nature
through language alone. As might be expected, the counter-reaction to the
state of society and its attitudes toward the environment found expression in
other media as well, in particular the rise of a cadre of American landscape
artists. The camera had not yet been perfected, and of course there was no
electronic media to compete for people’s attention, thus artists’ renditions of
various scenes, especially landscapes, were quite popular. Figure Kindred
Spirits, a rendering by A.B. Durand (1796-1886) of an artist and a poet out
for a hike amid a lush forest scene captures much of the essence of
transcendental thought, which had strongly influenced Durand’s style. The
offset of the human subjects, to left-of-center, is purposeful: the main
subject is nature, with humans merely a component. This theme carried
through many of the landscapes of the period, and helped to define what
became known, among others, as the “Hudson River School,” whose artists
depicted nature as an otherwise inexpressible manifestation of God. This is
further expressed in the painting, In the Heart of the Andes, by Frederic
Church (Figure In the Heart of the Andes). Here, the seemingly sole
theme is the landscape itself, but closer inspection (see detail in red square)
reveals a small party of people, perhaps engaged in worship, again offset
and virtually invisible amid the majesty of the mountains.
In the Heart of the Andes. The painting, dated 1859, depicts a
majestic landscape and closer inspection reveals a small party of
people near the bottom left. Source: Frederic Edwin Church via
Wikimedia Commons.
Other notable contributors to the transcendental movement were Henry
David Thoreau (1817-1862), abolitionist and author of Walden and Civil
Disobedience, Margaret Fuller (1810-1850), who edited the transcendental
journal “The Dial” and wrote Woman in the Nineteenth Century, widely
considered the first American feminist work, and Walt Whitman (1819-
1892) whose volume of poetry Leaves of Grass celebrates both the human
form and the human mind as worthy of praise.
It is important to recognize that the transcendental redefinition of our social
contract with the environment was holistic. Within it can be found not only
a new appreciation of nature, but also the liberation of the human mind
from convention and formalism, attacks on slavery, the need for racial
equality, concern for universal suffrage and women’s rights, and gender
equity. In many ways it was a repositioning of the ideals of the
enlightenment that had figured so prominently in the founding documents
of the republic. These social concerns are represented today within the
sustainability paradigm in the form of such issues as environmental justice,
consumer behavior, and labor relations.
Transcendentalism as a formal movement diminished during the latter half
of the 19" century, but it had a far-reaching influence on the way society
perceived itself relative to the environment. Perhaps no one is more
responsible for translating its aspirations into environmental public policy
than John Muir (1838-1914), a Scottish-borm immigrant who was heavily
influenced by Emerson’s writings (it is said that the young Muir carried
with him a copy of Nature from Scotland). The two first met in 1871 during
a camping trip to the Sierra Mountains of California. Upon learning of
Emerson’s planned departure, Muir wrote to him on May 8, 1871 hoping to
convince him to stay longer, “I invite you join me in a months worship with
Nature in the high temples of the great Sierra Crown beyond our holy
Yosemite. It will cost you nothing save the time & very little of that for you
will be mostly in Eternity” (Chou, 2003).
Muir was a naturalist, author, organizer (founder of the Sierra Club), and as
it turns out a remarkably effective political activist and lobbyist. His
association with Theodore Roosevelt (1858-1919, 26" president of the
United States), began with a 1903 campaign visit by Roosevelt to
California, where he specifically sought out Muir, whose reputation was by
then well known, as a guide to the Yosemite area (see Figure Roosevelt and
Muir).
Roosevelt and Muir Theodore Roosevelt
and John Muir at Yosemite National Park in
1903.
It was one of Muir’s special talents that he could bridge across their rather
different views on the environment (he a strict preservationist, Roosevelt a
practical outdoorsman). By all accounts they had frank but cordial
exchanges; for example, upon viewing the giant Sequoias, Muir remarked
to Roosevelt, “God has cared for these trees...but he cannot save them from
fools — only Uncle Sam can do that.” Roosevelt was so taken with his
companion that he insisted they avoid political crowds and camp together
overnight in the mountains.
The subsequent legacy of the Roosevelt administration in the name of
conservation, even by today’s standards, was significant. Known as the
“conservation president,” Roosevelt was responsible for 225 million acres
of land added to the U.S. Forest Service, and the creation of 50 wildlife
refuges and 150 national forests representing, in total, 11 percent of the total
land area of the 48 contiguous states.
The Role of Industry
Today the behavior of industry toward the environment is often portrayed as
either indifferent or hostile, whether true or not, and it was no different
during the formative period of American conservation. The industries of the
day — agriculture, timber, and mining — enabled by the major transportation
sector — railroads and steamboats — had little incentive to manage their
emissions to the environment responsibly, or to use natural resources
wisely. Regulations were few, the science underpinning environmental
impacts was nascent, the commons itself was viewed as essentially infinite,
and however misguided, exploitation of resources and the generation of a
certain amount of waste was seen as a necessary byproduct of expansion,
job creation, and social well-being. And yet, as human-created
organizations go, industries are extraordinarily sensitive to economic
conditions. If the sustainability paradigm is to be believed, then economic
viability is of paramount concern and the engagement of industrial forces
must of necessity be part of its enactment. These are the engines that
provide employment, and that control large quantities of capital for
investment. Further, viewed from the life cycle perspective of the flow of
materials (refer to Module Life Cycle Assessment), products that turn raw
materials into mostly waste (defined here as a quantity of material that no
one values, as opposed to salable products) are simply inefficient and
reduce profitability.
The Oregon Trail. The painting, dated 1869, depicts the westward
migration of settlers via wagon trains, on horseback, and by foot.
Source: Albert Bierstadt via Wikimedia Commons.
As noted in Resource Efficiency above, industrial activities during this time
were responsible for significant environmental degradation. Policy
reformers of the day, such as Carl Schurz (as secretary of the Interior)
turned their attention in particular to land reforms, which impacted the
expansion of railroads, and forest preservation. And yet, industry played an
unquestionable role as enablers of societal shifts occurring in America by
making goods and services available, increasing the wealth of the emerging
middle class, and in particular providing relatively rapid access to
previously inaccessible locations — in many cases the same locations that
preservationists were trying to set aside. Reading, hearing stories about, and
looking at pictures of landscapes of remote beauty and open spaces was
alluring and stirred the imagination, but being able to actually visit these
places firsthand was an educational experience that had transformative
powers. Alfred Bierstadt’s The Oregon Trail (Figure The Oregon Trail),
painted in 1868, depicts the westward migration of settlers via wagon trains,
on horseback, and simply walking — a journey, not without peril, that took
about six months. The next year saw the completion of the transcontinental
railroad, and within a few years it became possible to complete the same
journey in as little as six days in comparative comfort and safety.
The movement to designate certain areas as national parks is an illustrative
example of the role of industry in promoting land conservation, thereby
setting in motion subsequent large conservation set-asides that reached their
zenith during the Roosevelt administration. It began, in 1864, with the
efforts of several California citizens to have the U.S. Congress accept most
of Yosemite, which had been under the “protection” of the State of
California as a national preserve. The petition cited its value “for public
use, resort, and recreation,” reasoning that already reflected the combined
interests of the resource efficiency group, preservationists, and business
opportunists. Frederick Law Olmsted (1822-1903), the landscape architect
most well known for the design of New York’s Central Park, and an ardent
believer in the ability of open spaces to improve human productivity,
oversaw the initial efforts to manage the Yosemite area. Although the effort
was infused with renewed vigor after John Muir’s arrival in the late 1860s,
it wasn’t until 1906 that the park was officially designated.
In the meantime, similar interests had grown to name Yellowstone as a
national park, with the same basic justification as for Yosemite. Since there
were no States as yet formed in the region the pathway was more
straightforward, and was made considerably easier by the lack of interest by
timber and mining companies to exploit (the area was thought to have
limited resource value), and the railroads who, seeing potential for
significant passenger traffic, lobbied on its behalf. Thus the first national
park was officially designated in 1872, only three years after the completion
of the transcontinental railroad. Indeed, in relatively rapid succession the
Union Pacific Railroad got behind the Yosemite efforts, and the Northern
Pacific Railroad lobbied heavily for the creation of parks at Mount Rainier
(1899) and Glacier (1910). By 1916, when the National Park Service was
formed, sixteen national parks had been created. States too began to see
value in creating and, to a degree, preserving open spaces, as evidenced by
New York’s Adirondack Park (1894), still the largest single section of land
in the forty-eight contiguous states dedicated to be “forever wild.”
Results of the American Conservation Movement
With the advent of the First World War, and subsequent political, social, and
economic unrest that lasted for another thirty years, actions motivated by
the conservation movement declined. The coalition between the resource
efficiency group and those wishing to preserve nature, always
uncomfortable, was further eroded when it became clear that the main
reason Congress was “setting aside” various areas was mainly to better
manage commercial exploitation. And yet, the period from 1850 to 1920
left a remarkable legacy of environmental reform, and laid the foundation
for future advances in environmental policy. In summary, the conservation
movement accomplished the following:
e Redefined the social contract between humans and the environment,
establishing a legacy of conservation as part of the American character,
and a national model for the preservation of natural beauty.
e Invented the concept of national parks and forests, wildlife refuges,
and other sites for commercial and recreational uses by society.
¢ Developed the first scientific understanding of how the environment
functioned, integrating the scientific approach to resource management
into government policy.
e Pioneered technological practices to improve resource management.
e Established the major federal institutions with responsibility for land
and resource conservation.
e Communicated the impact of pollution on human health and welfare.
e Through publications and travel, exposed many to the beauty of the
natural environment and the consequences of human activities.
e Finally, although sustainability as a way of envisioning ourselves in
relation to the environment was still many years away, already its three
principal elements, imperfectly integrated at the time, are seen clearly
to be at work.
References
Carman, H.J., Tugwell, R.G., & True, R.H. (Eds.). (1934). Essays upon
field husbandry in New England, and other papers, 1748-1762, by Jared
Eliot. New York: Columbia University Press.
Chou, P.Y. (Ed.). (2003). Emerson & John Muir. WisdomPortal. Retrieved
December 11, 2011 from http://www.wisdomportal.com/Emerson/Emerson-
JohnMuir.html.
Environmental Risk Management
In this module, the following topics are covered: 1) the basic elements of
the sustainability paradigm through the evolution of U.S. environmental
policy, and 2) the role of risk management as modern environmental policy
has been implemented.
Learning Objectives
After reading this module, students should be able to
e trace the basic elements of the sustainability paradigm through the
evolution of U.S. environmental policy, including the National
Environmental Policy Act of 1970
e understand the role of risk management as modern environmental
policy has been implemented
General Definitions
For most people, the concept of risk is intuitive and, often, experiential; for
instance most people are aware of the considerably greater likelihood of
suffering an injury in an automobile accident (116/100 million vehicle
miles) versus suffering an injury in a commercial airplane accident
(0.304/100 million airplane miles). Environmental risk can be defined as
the chance of harmful effects to human health or to ecological systems
resulting from exposure to any physical, chemical, or biological entity in
the environment that can induce an adverse response (see Module Risk
Assessment Methodology for Conventional and Alternative
Sustainability Options for more detail on the science of risk assessment).
Environmental risk assessment is a quantitative way of arriving at a
statistical probability of an adverse action occurring. It has four main steps:
1. Identification of the nature and end point of the risk (e.g. death or
disability from hazardous chemicals, loss of ecological diversity from
habitat encroachment, impairment of ecosystem services, etc.)
2. Development of quantitative methods of analysis (perturbation-effect,
dose-response)
3. Determination of the extent of exposure (i.e. fate, transport, and
transformation of contaminants to an exposed population), and
4. Calculation of the risk, usually expressed as a statistical likelihood.
Risk management is distinct from risk assessment, and involves the
integration of risk assessment with other considerations, such as economic,
social, or legal concerns, to reach decisions regarding the need for and
practicability of implementing various risk reduction activities. Finally, risk
communication consists of the formal and informal processes of
communication among various parties who are potentially at risk from or
are otherwise interested in the threatening agent/action. It matters a great
deal how a given risk is communicated and perceived: do we have a
measure of control, or are we subject to powerful unengaged or arbitrary
forces?
The Beginnings of Modern Risk Management
The beginnings of environmental risk management can be traced to the
fields of public health, industrial hygiene, and sanitary engineering, which
came into prominence in the latter decades of the 19" century and
beginning of the 20". The spread of disease was a particularly troublesome
problem as the country continued to urbanize. For instance if you lived your
life in, say, Chicago during the period 1850-1900 (a typical lifespan of the
day), you had about a 1 in 100 chance of dying of cholera (and a 1 in 2000
chance of dying of typhoid), of which there were periodic epidemics spread
by contaminated drinking water. Chicago's solution was to cease polluting
its drinking water source (Lake Michigan) by reversing the flow of its
watercourses so that they drained into the adjacent basin (the Mississippi).
The widespread chlorination of municipal water after 1908 essentially
eliminated waterborne outbreaks of disease in all major cities (with some
notable exceptions—the outbreak of chlorine-resistant Cryptosporidium
parvum in Milwaukee's drinking water in 1993 resulted in the infection of
403,000 people with 104 deaths).
Parallel work on the effects of chemical exposure on workers (and poor
working conditions in general) were pioneered by Alice Hamilton (1869-
1970), who published the first treatise on toxic chemical exposure
"Industrial Poisons in the United States" in 1925. Hamilton is considered
the founder of the field of occupational health. In 1897 she was appointed
professor of pathology at the Women's Medical School of Northwestern
University, and in 1902 she accepted the position of bacteriologist at the
Memorial Institute for Infectious Diseases in Chicago. Dr. Hamilton joined
Jane Addams's Hull House, in Chicago, where she interacted with
progressive thinkers who often gravitated there, and to the needs of the poor
for whom Hull House provided services.
Environmental Contamination and Risk
Events during the period 1920-1950 took an unfortunate turn. Global
conflicts and economic uncertainty diverted attention from environmental
issues, and much of what had been learned during the previous hundred
years, for example about soil conservation and sustainable forestry, ceased
to influence policy, with resultant mismanagement on a wide scale (see
Figures Texas Dust Storm and Clear Cutting, Louisiana, 1930).
Texas Dust Storm. Photograph shows a dust storm
approaching Stratford, TX in 1935. Source: NOAA via
Wikimedia Commons
Clear Cutting, Louisiana, 1930. Typical cut-
over longleaf pine area, on Kisatchie National
Forest. Areas of this type were the first to be
planted on this forest. Circa 1930s. Source: Wait,
J.M. for U.S. Forest Service. U.S. Forest Service
photo courtesy of the Forest History Society,
Durham, N.C.
In the aftermath of the World War II, economic and industrial activity in the
United States accelerated, and a consumer-starved populace sought and
demanded large quantities of diverse goods and services. Major industrial
sectors, primary metals, automotive, chemical, timber, and energy expanded
considerably; however there were still few laws or regulations on waste
management, and the ones that could and often were invoked (e.g. the
Rivers and Harbors Act of 1899) were devised in earlier times for problems
of a different nature. The Module Systems of Waste Management
provides a more detailed accounting of the current framework for managing
waste. Here we recount the circumstances that eventually resulted in the
promulgation of environmental risk as a basis for public policy, with
subsequent passage of major environmental legislation.
Zinc Smelter. Photograph shows a
local smelter in a small valley town
in Pennsylvania with, essentially,
uncontrolled emissions. Source: The
Wire Mill, Donora, PA, taken by
Bruce Dresbach in 1910. Retrieved
from the Library of Congress
If there were any doubts among American society that the capacity of the
natural environment to absorb human-caused contamination with
acceptably low risk was indeed infinite, these were dispelled by a series of
well-publicized incidents that occurred during the period 1948-1978. Figure
Zinc Smelter shows a local smelter in a small valley town in Pennsylvania
with, essentially, uncontrolled emissions. During periods of atmospheric
stability (an inversion), contaminants became trapped, accumulated, and
caused respiratory distress so extraordinary that fifty deaths were recorded.
Figure Noon in Donora illustrates the dramatically poor air quality, in the
form of reduced visibility, during this episode. Such incidents were not
uncommon, nor were they limited to small American towns. A well-
documented similar episode occurred in London, England in 1952 with at
least 4000 deaths, and 100,000 illnesses resulting.
Noon in Donora.
Photograph, dated October
29, 1948, illustrates the
extremely poor air quality in
the Pennsylvania town at the
time. Source: NOAA
The generally poor state of air quality in the United States was initially
tolerated as a necessary condition of an industrialized society. Although the
risks of occupational exposure to chemicals was becoming more well
known, the science of risk assessment as applied to the natural environment
was in its infancy, and the notion that a polluted environment could actually
cause harm was slow to be recognized, and even if true it was not clear
what might be done about it. Nevertheless, people in the most contaminated
areas could sense the effects of poor air quality: increased incidence of
respiratory disease, watery eyes, odors, inability to enjoy being outside for
more than a few minutes, and diminished visibility.
Cuyahoga River Fire, 1969. Photograph illustrates a 1969 fire
on the Cuyahoga River, one of many fires during the time
period. Source: NOAA.
Environmental degradation of the era was not limited to air quality.
Emissions of contaminants to waterways and burial underground were
simple and common ways to dispose of wastes. Among the most infamous
episodes in pollution history were the periodic fires that floated through
downtown Cleveland, Ohio on the Cuyahoga River, causing considerable
damage (Figure Cuyahoga River Fire 1969), and the discovery of buried
hazardous solvent drums in a neighborhood of Niagara Falls, NY in 1978, a
former waste disposal location for a chemical company (Figure Love
Canal).
Infrared aerial photo of Love Canal area (taken in spring 1978) showing
99th Street elementary school in center, two rings of homes bordering the
landfill and LaSalle Housing Development in upper right. White patchy
areas indicate barren sections where vegetation will not grow, presumably
due to leaching chemical contamination.
jit et rad
f eye
«
ee ae Ee ?
ai 2%
rts
= a
ein 5
Love Canal. The Love Canal region of Niagara Falls,
NY, 1978 showing the local grade school and neighboring
houses. Source: New York State Department of Health
(1981, April). Love Canal: A special report to the
Governor and Legislature, p. 5.
Risk Management as a Basis for Environmental Policy
Environmental scientists of the day were also alarmed by the extent and
degree of damage that they were documenting. The publication of Silent
Spring in 1962 by Rachel Carson (1907-1964), about the impact of the
widespread and indiscriminate use of pesticides, was a watershed moment,
bringing environmental concerns before a large portion of the American,
and global, public. Carson, a marine biologist and conservationist who
initially worked for the U.S. Bureau of Fisheries, became a full time nature
writer in the 1950s. She collected scientifically documented evidence on the
effects of pesticides, particularly DDT, heptachlor, and dieldrin, on humans
and mammals, and the systemic disruption they caused to ecosystems.
Silent Spring is credited with bringing about a ban on the use of DDT in the
United States, and setting in motion a chain of events that would ultimately
result in the transformation of environmental public policy from one based
on the problems and attitudes that brought about nineteenth century
conservation, to one based on the management of risks from chemical
toxins. The U.S. Environmental Protection Agency was established in 1970,
just eight years after the publication of Silent Spring. The same year Earth
Day was created.
As noted, the modules in the Chapter Modern Environmental
Management contain a comprehensive treatment of the major laws and
regulations that underpin the risk management approach to environmental
policy. However it is worth considering one law in particular at this point,
the National Environmental Policy Act of 1970 (NEPA), because it
provides a legal basis for U.S. environmental policy, and lays out its terms
clearly and unambiguously. NEPA established a national goal to create and
maintain "conditions under which [humans] and nature can exist in
productive harmony, and fulfill the social, economic and other requirements
of present and future generations of Americans[emphasis added]" (NEPA,
1970). Further, NEPA saw the need for long term planning, to "fulfill the
responsibilities of each generation as trustee of the environment for
succeeding generations," for equity "to assure for all Americans safe,
healthful, productive, and esthetically and culturally pleasing
surroundings," and for economic prosperity as we "achieve a balance
between population and resource use that will permit high standards of
living and a wide sharing of life's amenities" (NEPA, 1970). Although the
exact word "sustainable" does not appear, NEPA is in all major respects
congruent with the goals of the Brundtland Report (written 17 years later,
see Chapter Introduction to Sustainability: Humanity and the
Environment), retains the character of American conservation, and
anticipates the need to integrate environmental quality with social and
economic needs.
Every four to six years the U.S. EPA releases its Report on the
Environment, a collection of data and analysis of trends on environmental
quality. It is quite comprehensive; reporting on an array of measures that
chart progress, or lack thereof, on human impacts on the environment and,
in turn, the effects of our actions on human health. It is difficult to
summarize all the information available in a concise way, however most
measures of human exposure to toxic chemicals, dating in many cases back
to the late 1980s, show clear downward trends, in some cases dramatically
so (for example DDT in human tissues, lead in blood serum, exposure to
hazardous wastes from improper disposal, exposure to toxic compounds
emitted to the air). In addition, many of other indicators of environmental
quality such as visibility, drinking water quality, and the biodiversity of
streams, show improvement. These are success stories of the risk
management approach to environmental quality. On the other hand, other
measures, such as hypoxia in coastal waters, quantities of hazardous wastes
generated, and greenhouse gases released are either not improving or are
getting worse.
References
National Environmental Policy Act of 1970, 42 U.S.C., 4321, et seq.
Sustainability and Public Policy
In this module, the problem-driven nature of policy development is discussed.
Learning Objectives
After reading this module, students should be able to
e understand the problem-driven nature of policy development, from relatively local agricultural problems to
regional problems often driven by industrial development to global problems associated with population-
driven human consumption
Complex Environmental Problems
NEPA, both in tone and purpose, was in sharp contrast to the many environmental laws that followed in the 1970s
and 1980s that defined increasingly proscriptive methods for controlling risks from chemical exposure (this is
sometimes termed the "command-and-control" approach to environmental management). In many ways these laws
and regulations are ill-suited to the types of environmental problems that have emerged in the past twenty years.
Whereas the focus of our environmental policy has been on mitigating risk from local problems that are chemical —
and media — (land, water, or air) specific, the need has arisen to address problems that are far more complex, multi-
media, and are of large geographic, sometimes global, extent.
An early example of this type of shift in the complexity of environmental problems is illustrated by the
phenomenon of acidic rainfall, a regional problem that occurs in many areas across the globe. Although the
chemical cause of acid rain is acidic gases (such as sulfur dioxide and nitrogen oxides) released into the
atmosphere from combustion processes (such as coal burning), the problem was made considerably worse because
of the approach to problem solving typical of the day for episodes such as the Donora disaster (see Figures Zinc
Smelter and Noon in Donora).
Hydrogen ion concentrations as pH for 1996
from measurements made at the Central Analytical Laboratory
National Atmospheric Deposition Program/National Treads Network
Printed: 09/01/97
Hydrogen Ion Concentrations as pH for 1996.
Figure shows the distribution in rainfall pH in the
United States for the year 1996. Source: National
Atmospheric Deposition Program/National Trends
Network via National Park Service.
In order to prevent the local accumulation of contaminants, emission stacks were made much taller, effectively
relying on the diluting power of the atmosphere to disperse offending pollutants. The result was a significant
increase in the acidity of rainfall downwind of major sources, with associated impacts on aquatic and forest
resources. Figure Hydrogen Jon Concentrations as pH for 1996 shows this pattern for the eastern United States
in 1996. A more comprehensive solution to this problem (short of replacing coal as a fuel source), has involved
integrated activity on many fronts: science to understand the impacts of acid rain, technology to control the release
of acidic gases, politics in the form of amendments to the Clean Air Act, social equity that defined the role of
regional responsibilities in the face of such large geographic disparities, and economics to understand the total
costs of acid rain and design markets to spread the costs of control. Although acidic rainfall is still an issue of
concern, its impacts have been mitigated to a significant degree.
Sustainability as a Driver of Environmental Policy
The level of complexity illustrated by the acid rain problem can be found in a great many other environmental
problems today, among them:
e Hypoxic conditions in coastal regions of the world caused by excessive release of nutrients, principally
dissolved nitrogen and phosphorous from artificial fertilizer applied to crops (in addition to the Gulf of
Mexico and Chesapeake Bay in the United States, there are over 400 such areas worldwide),
e Stratospheric ozone depletion caused by the release of certain classes of chlorofluorocarbon compounds used
as propellants and refrigerants (with increases in the incident of skin cancers and cataracts),
e Urbanization and sprawl, whereby the population density in urban areas, with its attendant problems
(degradation of air and water quality, stormwater management, habitat destruction, infrastructure renewal,
health care needs, traffic congestion, loss of leisure time, issues of social equality), continues to grow (for
example eighty percent of the population of the United States, about fifty percent of global, now lives in
urban regions),
e Global climate change, and its resultant impacts (increases in temperature and storm and flooding frequency,
ocean acidification, displacement of human populations, loss of biodiversity, sea-level rise), caused by the
human-induced emission of greenhouse gases.
Problems such as these, which require highly integrated solutions that include input from many disciplines and
problems have certain key characteristics:
e There is not universal agreement on what the problem is — different stakeholders define it differently.
e There is no defined end solution, the end will be assessed as "better" or "worse."
e The problem may change over time.
e There is no clear stopping rule — stakeholders, political forces and resource availability will make that
determination on the basis of "judgments."
e The problem is associated with high uncertainty of both components and outcomes.
e Values and societal goals are not necessarily shared by those defining the problem or those attempting to
make the problem better.
Wicked problems are not confined to environmental issues, for example the same characteristics arise for problems
such as food safety, health care disparities, and terrorism, but in the context of environmental policy they create the
need to reassess policy approaches and goals, laws and regulations, as well as methods and models for integrated
research.
Table The Evolution of U.S. Environmental Policy summarizes the major attributes of U.S. environmental policy
as it has evolved over the past two centuries. To most observers it would seem to be true that advances in public
policy, in any realm, are driven by problems, real and perceived, that require systemic solutions. Environmental
policy is no exception. Early conservationists were alarmed at the inefficiencies of human resource management
and the encroachment of humans on unspoiled lands. During the 20" century many groups: scientists, economists,
politicians, and ordinary citizens, became alarmed and fearful of the consequences of toxic pollutant loads to the
environment that included localized effects on human health and well-being. And now, as we proceed into the 21%
century, an array of complex problems that have the potential to alter substantially the structure and well-being of
large segments of human societies, calls for a renewal and reassessment of our approach to environmental policy.
This has, thus far, proven to be a difficult transition. Many of these complex problems have multiple causes and
impacts, affect some groups of people more than others, are economically demanding, and are often not as visibly
apparent to casual observers as previous impacts, nor are the benefits perceived to be commensurate with costs.
Devising a regulatory strategy for such problems requires an adaptive and flexible approach that current laws do
not foster.
Focus
Outcome
Principal
Activity
Economic
Focus
Regulatory
Activity
Conceptual
Model
Disciplinary
Approach
1850-1920
Conservation/sanitation
Land
preservation/efficiency/control
of disease
Resource management
reform/simple contaminant
controls
Profit maximization/public
health
Low
Expansion vs. preservation
Disciplinary and insular
1960-1990
Media/site/problem
specific
Manage
anthropocentricand
ecological risk
Compliance/
remediation/technological
emphasis on problem
solving
Cost minimization
Heavy
Command-and-control
Multidisciplinary
1990-present
Complex regional/ global
problems
Global sustainable
development
Integration of social,
economic, and
technological information
for holistic problem solving;
Strategic investments/long-
term societal well-being
Adaptive and Flexible
Systems/life cycle approac!
Interdisciplinary/Integrativ
The Evolution of U.S. Environmental Policy Table summarizes the major attributes of U.S. environmental policy :
et al. (2009).
References
Batie, S. S. (2008, December). Wicked problems and applied economics. American Journal of Agricultural
Economics, 90, 1176-1191 doi: 10.1111/j.1467-8276.2008.01202.x
Fiksel, J., Graedel, T., Hecht, A. D., Rejeski, D., Saylor, G. S., Senge, P. M., Swackhamer, D. L., & Theis, T. L.
(2009). EPA at 40: Bringing environmental protection into the 21° century. Environmental Science and
Technology, 43, 8716-8720. doi: 10.1021/es901653f
Kreuter, M. W., DeRosa, C., Howze, E. H., & Baldwin, G. T. (2004, August). Understanding wicked problems: A
key to advancing environmental health promotion. Health, Education and Behavior, 31, 441-54. doi:
10.1177/1090198104265597
Public Health and Sustainability
In this module, the following topics will be covered: 1) definition of public
health, 2) public health impacts of non-sustainable development, 3) key
public health impacts of climate change.
Learning Objectives
After reading this module, students should be able to
e understand what public health is
e recognize public health impacts of non-sustainable development
e identify key public health impacts of climate change
Introduction
“Much discussion about sustainability treats the economy, livelihoods,
environmental conditions, our cities and infrastructure, and social relations
as if they were ends in themselves; as if they are the reason we seek
sustainability. Yet their prime value is as the foundations upon which our
longer-term health and survival depend.” (McMichael, 2006)
Ecological sustainability is more than just continuing the resource flows of
the natural world to sustain the economic machine, while maintaining
diversity of species and ecosystems. It is also about sustaining the vast
support systems for health and life which could be considered the real
bottom line of sustainability. Before examining the public health effects of
non-sustainable development, we should define public health.
e The website for UIC’s School of Public Health says “we are passionate
about improving the health and well-being of the people of Chicago,
the state of Illinois, the nation and the world.”
¢ The Illinois Department of Public Health is responsible for protecting
the state's 12.4 million residents, as well as countless visitors, through
the prevention and control of disease and injury.”
e The New Zealand Ministry of Health defines it as “the science and art
of promoting health, preventing disease and prolonging life through
organized efforts of society.”
e The National Resources Defense Council an NGO devoted to
environmental action, states that public health is “the health or
physical well-being of a whole community.”
Impacts of Non-Sustainable Development
We have built our communities in ways that are unsustainable from many
aspects. Not only does development create urban sprawl, impact land use,
and fuel consumption, we can identify negative health consequences related
to these development trends.
Obesity
If our communities are not walkable or bikeable, we need to drive to
schools, shops, parks, entertainment, play dates, etc. Thus we become more
sedentary. A sedentary lifestyle increases the risk of overall mortality (2 to
3-fold), cardiovascular disease (3 to 5-fold), and some types of cancer,
including colon and breast cancer. The effect of low physical fitness is
comparable to that of hypertension, high cholesterol, diabetes, and even
smoking (Wei et al., 1999; Blair et al., 1996).
Economic Segregation
Walkable and safe communities provide sidewalks, bike paths, proximity,
and connections to community services such as grocery stores, schools,
health care, parks, and entertainment. Community design that creates a
segregated housing environment with only expensive housing and no
affordable housing segregates people by socio-economic level (i.e. poor
from non-poor) and this generally leads to segregation by race. Lack of
physical activity will occur in neighborhoods with no good green and safe
recreational sites. If we have poor public transit systems partly due to lack
of density (only more expensive, low-density housing) and our love of the
automobile, then we have increased emissions that contribute to global
warming.
The Olympics as an Example
A natural experiment during the 1996 Summer Olympic Games in Atlanta
shows the impact of car use on health. During the games, peak morning
traffic decreased 23% and peak ozone levels decreased 28%. Asthma-
related emergency room visits by children decreased 42% while children’s
emergency visits for non-asthma causes did not change during same period
(Friedman, Powell, Hutwagner, Graham, & Teague, 2001). We also saw that
with the Beijing Olympics in 2008 where driving days were rationed, more
than 300,000 heavy-emitting vehicles (about 10% of total) were barred
from the city’s administrative area in order to decrease pollution for athletes
and visitors This reduced the number of vehicles by about 1.9 million or
60% of the total fleet during the Olympic Games. Emissions of black
carbon, carbon monoxide and ultrafine particles were reduced by 33%,
47%, and 78% respectively compared to the year before the Olympics.
Frequency of respiratory illnesses during the 2008 games were found to be
significantly less in certain populations compared to previous years and this
was hypothesized to be related to the reduction of vehicles on the road
(Wang et al., 2009; Jentes et al., 2010).
Minutes Americans Walk per Day
Source: National Household Travel
Survey, 2001, USDOT
Figure Minutes Americans Walk per Day shows the average time
Americans spend walking a day. People who walk to and from public transit
get an fair amount of physical activity related to using transit, thus the name
given to modes of transit that do not involve driving: active transit. Those
people who did not own a car or were not a primary driver had higher
walking times (Besser & Dannenberg, 2005).
Water Quality
Increasing numbers of roads and parking lots are needed to support an
automobile transportation system, which lead to increased non-point source
water pollution and contamination of water supplies (road runoff of oil/gas,
metals, nutrients, organic waste, to name a few) with possible impacts on
human health. Increased erosion and stream siltation causes environmental
damage and may affect water treatment plants and thus affect water quality.
Social Capital
On the social sustainability side, we can look at social capital otherwise
defined as the “connectedness” of a group built through behaviors such as
social networking and civic engagement, along with attitudes such as trust
and reciprocity. Greater social capital has been associated with healthier
behaviors, better self-rated health, and less negative results such as heart
disease. However, social capital has been diminishing over time. Proposed
causes include long commute times, observed in sprawling metropolitan
areas. Past research suggests that long commute times are associated with
less civic participation; Robert Putnam suggests that every ten additional
minutes of commuting predicts a 10% decline in social capital (Besser,
most long commutes.
As of 2011, according to an article in the Chicago Tribune, Chicago
commuting times are some of the worst — with Chicagoans spending 70
hours per year more on the road than they would if there was no congestion
—up from 18 hours in 1982. They have an average commute time of 34
minutes each way. These drivers also use 52 more gallons per year per
commuter, increasing their costs and pollution.
Residents of sprawling counties were likely to walk less during leisure time,
weigh more, and have greater prevalence of hypertension than residents of
compact counties (Ewing, Schmid, Killingsworth, Zlot, & Raudenbush,
2003).
While more compact development is found to have a negative impact on
weight, we also find that individuals with low BMI are more likely to select
locations with dense development. This suggests that efforts to curb sprawl,
and thereby make communities more exercise-friendly, may simply attract
those individuals who are predisposed to physical activity (Plantinga &
Bernell, 2007).
Impacts of Climate Change
Public health studies have been conducted with regard to many of the
predicted environmental effects of climate change. Thus, it is somewhat
easier to examine the public health implications of this outcome of
unsustainable behavior. Figure How Climate Change Affects Population
describes the pathways by which climate change affects public health. To
the left we see the natural and anthropogenic, or human-caused activities
that affect climate change, which result in climatic conditions and
variability; if we can mitigate those events we can reduce climate change.
These activities first result in environmental impacts such as severe weather
events, disturbed ecosystems, sea-level rise, and overall environmental
degradation. Those impacts can then result in a broad range of health effects
that we can adapt to, to a certain extent. These impacts are generally
categorized into three areas: heat induced morbidity and mortality,
infectious diseases, and impacts due to the effect of extreme weather such
as flooding and drought on the social welfare of the population.
Health effects
Greenhouse gas
emissions due ta
hurnan activity
Environmental effects
Thermal stress: deaths, illness
Extreme weather (asthma, allergies)
events Injury/death from floods, storms,
“frequency cyclones, bushfires
“severity Effect of these events onfood yields
"geography
Microbial proliferation:
Changes in Food poisoning—Salmonetia spp,
frequency etc; unsafe drinking water
intensity, and
Climate phate Effects on ecosystems;
change “temperature : Changes in vector-pathogen-host
“precipitation Lela peel on relations and in infectious disease
humidity p P geography/seasonality - e.g.
«wind patterns Malaria dengue, tickborne viral
disease, schistosomiasis
Sea-level rise:
Salination of coastal
land and freshwater;
storm surges
Impaired crop, livestock and
fisheries yields, leading to impaired
nutrition, health, survival
Natural climate determinants:
terrestrial, solar, planetary, orbital
Environmental degradation:
Land, coastal ecosystems,
fisheries
Loss of livelihoods, displacement,
leading to poverty and adverse
health: mental health, infectious
diseases, malnutrition, physical risks
How Climate Change Affects Population Diagram summarizing the
main pathways by which climate change affects population health.
Source:Created by Cindy Klein-Banai, based on McMichael et al.,
2006
Measurement of health effects from climate change can only be very
approximate. One major study, by the World Health Organization (WHO),
was a quantitative assessment of some of the possible health impacts that
looked at the effects of the climate changes since the mid-1970s and
determined that this may have resulted in over 150,000 deaths in 2000. The
study concluded that the effects will probably grow in the future (World
Health Organization, 2009).
Extreme Weather
Climate change can influence heat-related morbidity and mortality,
generally a result of the difference between temperature extremes and mean
climate in a given area. Higher temperatures in the summer increase
mortality. Studies on the effects of heat waves in Europe indicate that half
of the excess heat during the European heat wave of 2003 was due to global
warming and, by inference, about half of the excess deaths during that heat
wave could be attributed to human-generated greenhouse gas emissions (see
& Nadelhoffer, 2007; McMichael, 2006). Urban centers are more
susceptible due to the urban heat island effect that produces higher
temperatures in urban areas as compared to the near-by suburbs and rural
areas. Lack of vegetation or evaporation, and large areas of pavement, in
cities result in an “Urban Heat Island,” where urban areas are warmer than
the neighboring suburban and rural areas (See Figure Sketch of an Urban
Heat-Island Profile). Adaptation can help reduce mortality through greater
prevention awareness and by providing more air-conditioning and cooling
centers.
wo
ao
Commercial
~ Suburban
Residential
co
ol
:
®
—
=
—
13°)
=
®
a
5
—
jong
°o
=]
4
a
®
ons
=
<x
@
—
oO
J)
Sketch of an Urban Heat-Island Profile. Source: Heat Island Group.
The reduction of extreme cold due to global warming, could reduce the
number of deaths due to low temperatures. Unlike for heat, those deaths are
usually not directly related to the cold temperature itself but rather to
influenza. Also, deaths related to cold spells would increase to a lesser
extent by (1.6%), while heat waves increase them by 5.7%.
Since volatile organic compounds are precursors of ozone, and VOC
emissions increase with temperature, this could lead to an increase in ozone
concentrations. For fifteen cities in the eastern United States, the average
number of days exceeding the health-based eight-hour ozone standard is
projected to increase by 60 percent (from twelve to almost twenty days each
summer) by the 2050s because of warmer temperatures (Lashof, & Patz,
2004). Pollen levels may increase with increased CO; levels since that
promotes growth and reproduction in plants. This will increase the
incidence of allergic reactions. Similarly, poison ivy will grow more and be
more toxic.
Infectious diseases are influenced by climate as pathogen survival rates are
strongly affected by temperature change. Diseases carried by birds, animals,
and insects (vector-born) — such as malaria, dengue fever, and dengue
hemorrhagic fever — may be influenced by temperature as mosquitoes are
sensitive to climate conditions such as temperature humidity, solar
radiation, and rainfall. For example, there has been a strengthening of the
relationship between the El Nino global weather cycle and cholera
outbreaks in Bangladesh. Increases in malaria in the highlands of eastern
Africa may be associated with local warming trends. Temperature also
affects the rate of food-born infectious disease. In general, however, it is
hard to isolate the effects of climate change that affect the transmission rate
and geographic boundaries of infectious disease from other social,
economic, behavioral, and environmental factors (see McMichael et al.,
2006). Increased precipitation from extreme rainfall events can cause
flooding which, especially in cities with combined sewer and stormwater
systems can be contaminated by sewage lines. This can happen when the
deep tunnels that carry stormwater in Chicago reach capacity and untreated
sewage then must be released into Lake Michigan. E. Coli levels in the lake
then increase, forcing beaches to close to prevent the spread of infection.
Diseases are re-emerging and emerging infectious due to intensified food
production in “factory” farms. Examples include mad cow disease (1980s in
Britain); the encroachment on rain forest by pig farmers exposed pigs and
farmers to the “Nipah” virus carried by rainforest bats that were seeking
food from orchards around the pig farms — driven by deforestation and the
drought of El Nino. This caused infection of pigs which lead to human
illness and more than one hundred deaths. Poultry farming (avian influenza
viruses) - crowded ‘factory farming’ may increase the likelihood of viral
virulence when there is no selective advantage in keeping the host bird
alive. Other food related issues are discussed in the next section.
Food Production
Climate change can influence regional famines because droughts and other
extreme climate conditions have a direct influence on food crops and also
by changing the ecology of plant pathogens (Patz et al., 2005).
There are likely to be major effects of climate change on agricultural
production and fisheries. This can be both positive and negative depending
on the direct effects of temperature, precipitation, CO>, extreme climate
variations, and sea-level rise. Indirect effects would have to do with
changes in soil quality, incidence of plant diseases and weed and insect
populations. Food spoilage will increase with more heat and humidity.
Persistent drought has already reduced food production in Africa. There
could be reduction in nutritional quality due to a reduction in the amount of
nitrogen crops incorporate when CO> levels increase.
Malnutrition will be increased due to drought, particularly poorer countries.
Increasing fuel costs also increase the cost of food, as we are already seeing
in 2011. Again, this incremental cost rise affects those who already spend a
large portion of their income on food and can contribute to malnutrition.
About one-third, or 1.7 billion, of all people live in water-stressed countries
and this is anticipated to increase to five billion by 2025. Frequency of
diarrhea and other diseases like conjunctivitis that are associated with poor
hygiene and a breakdown in sanitation may increase.
Lower Emissions
@ Higher Emissions
Avg No. of Yrs per Decade with EHW-like Summers
1980 2000 2020 2040 2060 2080
Projection for Future EHW-like Summers in
Chicago. The average number of summers per decade
with mortality rates projected to equal those of the
Chicago analog to the European Heat Wave of 2003.
Values shown are the average of three climate models
for higher (orange) and lower (yellow) emission
scenarios for each decade from 1980 to 2090 Source:
Hellmann et al., 2007.
Various studies suggest that increases in population at risk from
malnutrition will increase from 40-300 million people over the current 640
million by 2060 (Rosenzweig, Parry, Fischer & Frohberg, 1993). A more
recent study said that today 34% of the population is at risk and by 2050
this value would grow to 64-72%. Climate change is associated with
decreased pH (acidification) of oceans due to higher CO, levels. Over the
past 200 years ocean pH has been reduced by 0.1 units and the IPCC
predicts a drop of 0.14 to 0.35 units by 2100. This may affect shell-forming
organisms and the species that depend on them. There could be a reduction
in plankton due to the North Atlantic Gulf Stream (Pauly & Alder, 2005).
With already overexploited fish populations, it will be harder for them to
recover.
Natural disasters like floods, droughts, wildfires, tsunamis, and extreme
storms have resulted in millions of deaths over the past 25 years and
negatively affected the lives of many more. Survivors may experience
increased rates of mental health disorders such as post-traumatic stress
disorder. Wildfires reduce air quality, increasing particulate matter that
provokes cardiac and respiratory problems. Sea level rise will increase
flooding and coastal erosion. Indirect effects of rising sea levels include the
infiltration of salt water and could interfere with stormwater drainage and
sewage disposal. This could force coastal communities to migrate and
create refugees with health burdens such as overcrowding, homelessness,
and competition for resources. Air pollution is likely to be worse with
climate change. It can also lead to mobilization of dangerous chemicals
from storage or remobilize chemicals that are already in the environment.
Specific regional effects have may be more severe. Vulnerable regions
include temperate zones predicted to experience disproportionate warming,
areas around the Pacific and Indian Oceans that are currently subject to
variability in rainfall, and large cities where they experience the urban heat
island effect (Patz et al., 2005). The Chicago area is one urban area where
analysis has been performed to determine the specific health effects that are
projected due to climate change (see Figure Projection for Future EHW-
like Summers in Chicago). Those effects are similar to the ones described
above.
An evaluation of the reductions in adverse health effects that could be
achieved by 2020 in four major cities with a total population of 45 million
found that GHG mitigation would “reduce particulate matter and ozone
ambient concentrations by about 10% and avoid some 64,000 premature
deaths, 65,000 person-chronic bronchitis case, and 37 million days of
restricted activities (Cifuentes, Borja-Aburto, Gouveia, Thurston & Davis,
2001). The cities’ ozone levels are estimated to increase under predicted
future climatic conditions, and this effect will be more extreme in cities that
already suffer from high pollution. The estimates of elevated ozone levels
could mean a 0.11% to 0.27% increase in daily total mortality (Bell et al.,
2007). Therefore, reduction of GHG emissions, along with actions to
mitigate the effects of climate change are likely to reduce the public health
outcomes associated with climate change.
Conclusions
The implications of climate change on public health are broad and vast. The
interconnectedness of all of earth’s systems and human health is an area that
is a challenge to study; the climate change scenarios are variable. Public
health is directly tied to the human ecosystem that we create through our
unsustainable activities. The deterioration of public health on this planet is
perhaps the most important consequence of our own unsustainable choices.
Without good public health outcomes, human life on this planet is
threatened and ultimately our actions could cause significant changes in
human health, well-being and longevity. It is not the earth that is at stake - it
is humanity.
Review Questions
Exercise:
Problem:
Think about the major sources of energy: coal, nuclear and petroleum.
Name some health effects that are associated with each, as portrayed in
recent world events. Find one popular and one scientific source to
support this.
Exercise:
Problem: Describe three health impacts of climate change.
Exercise:
Problem:
Modern farming practices are meant to increase productivity and feed
the world solving the problems of malnutrition and starvation. How
would you argue for or against this?
Exercise:
Problem:
What are some outcomes that could be measured to determine if a
community is healthy?
Resources
Health Impacts of Climate Change — Society of Occupational and
Environmental Health http://www. youtube.com/watch?v=aLfhwaS677c
References
Bell, M. L., Goldberg, R., Hogrefe, C., Kinney, P. L., Knowlton, K., Lynn,
B.,... Patz, J. A. (2007). Climate change, ambient ozone, and health in 50
US cities. Climatic Change, 82, 61-76.
Besser L. M., & Dannenberg A. L. (2005, November). Walking to public
transit steps to help meet physical activity recommendations. American
Journal of Preventive Medicine, 29(4), 273-280.
Besser, L. M., Marcus, M., & Frumkin, H. (2008, March). Commute time
and social capital in the U.S. American Journal of Preventive Medicine,
34(3), 207-211.
Blair S. N., Kampert, J. B., Kohl III, H. W., Barlow, C. E., Macera, C. A.,
Paffenbarger, Jr, R. S., & Gibbons, L. W. (1996). Influences of
cardiorespiratory fitness and other precursors on cardiovascular disease and
all-cause mortality in men and women. Journal of American Medical
Association, 276(3), 205-210.
Cifuentes, L., Borja-Aburto, V. H., Gouveia, N., Thurston, G., & Davis, D.
L. (2001). Hidden health benefits of greenhouse gas mitigation. Science,
293(5533), 1257-1259.
Ewing, R., Schmid, T., Killingsworth, R., Zlot, A., & Raudenbush, S.
(2003, September/October). Relationship between urban sprawl and
physical activity, obesity, and morbidity. American Journal of Health
Promotion, 18(1), 49-57.
Friedman, M. S., Powell, K. E., Hutwagner, L., Graham, L. M., & Teague,
W. G. (2001). Impact of changes in transportation and commuting
behaviors during the 1996 Summer Olympic Games in Atlanta on air
quality and childhood asthma. JAMA: The Journal of the American Medical
Association, 285(7), 897-905.
Haines, A., Kovats, R. S., Campbell-Lendrum, D., & Corvalan, C. (2006).
Climate change and human health: Impacts, vulnerability and public health.
Journal of the Royal Institute of Public Health. 120, 585-596.
Hellmann, J., Lesht, B., & Nadelhoffer, K. (2007). Chapter Four — Health.
In Climate Change and Chicago: Projections and Potential Impacts.
Retrieved from
http://www.chicagoclimateaction.org/filebin/pdf/report/Chicago climate i
Jentes, E. S., Davis, X. M., MacDonald, S., Snyman, P. J., Nelson, H.,
Quarry, D., ... & Marano, N. (2010). Health risks and travel preparation
among foreign visitors and expatriates during the 2008 Beijing Olympic
and Paralympic Games. American Journal of Tropical Medical Hygene, 82,
466-472.
Lashof, D. A., & Patz, J. (2004). Heat advisory: How global warming
causes more bad air days. Retrieved from
http://www.nrdc.org/globalwarming/heatadvisory/heatadvisory.pdf.
McMichael, A. J. (2006) Population health as the ‘bottom-line’ of
sustainability: A contemporary challenge for public health researchers.
European Journal of Public Health, 16(6), 579-582.
McMichael, A. J., Woodruff, R. E., & Hales, S. (2006). Climate change and
human health: Present and future risks. Lancet, 367, 859-869.
Patz, J. A., Campbell-Lendrum, D., Holloway, T., & Foley, J. A. (2005).
Impact of regional climate change on human health. Nature, 438, 310-317.
Pauly, D., & Alder, J. (2005). Marine Fisheries Systems. In R. Hassan, R.
Scholes, & N. Ash (eds.), Ecosystems and Human Well - being: Current
State and Trends . (Vol. 1). Washington, D.C., Island Press.
Plantinga, A. J., & Bernell, S. (2007). The association between urban
sprawl and obesity: Is it a two-way street?, Journal of Regional Science,
47(5), 857-879.
Rosenzweig, C., Parry, M. L., Fischer, G., & Frohberg, K. (1993). Climate
change and world food supply. Research Report No. 3. Oxford, U.K. :
Oxford University, Environmental Change Unit.
Wang, X., Westerdahl, D., Chen, L., Wu, Y., Hao, J., Pan, X., Guo, X., &
Zhang, K. M. (2009). Evaluating the air quality impacts of the 2008 Beijing
Olympic Games: On-road emission factors and black carbon profiles.
Atmospheric Environment, 43, 4535-4543.
Wei, M., Kampert, J. B. , Barlow, C. E. , Nichaman, M. Z. , Gibbons, L. W.,
Paffenbarger, Jr., R. S., & Blair, S. N. (1999). Relationship between low
cardiorespiratory fitness and mortality in normal-weight, overweight, and
obese men. Journal of the American Medical Association, 282(16), 1547-
1553,
World Health Organization. (2009). Climate change and human health. Fact
sheet, July 2005. Retrieved from
http://www.who.int/globalchange/news/fsclimandhealth/en/index.html.
Glossary
morbidity
The relative frequency of occurrence of a disease.
mortality
The number of deaths that occur at a specific time, in a specific group,
or from a specific cause.
post-traumatic stress disorder
PTSD - a psychological condition affecting people who have suffered
severe emotional trauma as a result of an experience such as combat,
crime, or natural disaster, and causing sleep disturbances, flashbacks,
anxiety, tiredness, and depression.
volatile organic compounds
(VOC - an organic compound that evaporates at a relatively low
temperature and contributes to air pollution, e.g. ethylene, propylene,
benzene, or styrene).
urban sprawl
Any environment characterized by (1) a population widely dispersed in
low density residential development; (2) rigid separation of homes,
shops, and workplaces; (3) a lack of distinct, thriving activity centers,
such as strong downtowns or suburban town centers; and (4) a network
of roads marked by large block size and poor access from one place to
another) has been found to correlate with increased body mass index.
Climate and Global Change — Chapter Introduction
In this module, the Chapter Climate and Global Change is introduced,
previewing the content of the modules included in the chapter.
Module by: Jonathan Tomkin
The Earth’s climate is changing. The scientific consensus is that by altering
the composition of the atmosphere humans are increasing the average
temperature of the Earth’s surface. This process has already begun — the
planet is measurably warmer than it was at the start of the last century — but
scientists predict the change that will occur over the 21st century will be
even greater. This increase will have unpredictable impacts on weather
patterns around the globe. We are all experiencing climate change. Our
descendants will likely experience far more.
This chapter focuses on the science of climate change. We recognize that
climate change can be a controversial subject, and that prescriptions for
solutions quickly take on a political character, which can raise suspicions of
bias. Some argue that the climate is too complicated to predict, and others
suggest that natural variations can explain the observed changes in the
climate.
These objections have some merit. It should be no surprise that the Earth’s
climate is a complicated subject. First, the atmosphere is vast: it extends
over 600 km (370 miles) above the ground, and it weighs over five
quadrillion tons (that’s a five followed by 15 zeros). Second, the
atmosphere is a dynamic system, creating blizzards, hurricanes,
thunderstorms, and all the other weather we experience. And it is true that
this dynamic system is largely controlled by natural processes — the Earth’s
climate has been changing continually since the atmosphere was produced.
And yet scientists can still confidently say that humans are responsible for
the current warming. We can do this because this complicated system obeys
underlying principles. In the modules Climate Processes; External and
Internal Controls and Milankovitch Cycles and the Climate of the
Quaternary, we will describe how these principles work, and how they
have been observed by scientists. We can then use these principles to
understand how, by producing greenhouse gases, humans are altering the
physical properties of the atmosphere in such a way as to increase its ability
to retain heat.
In the module Modern Climate Change we show how this theoretical
prediction of a warming world is borne out by ever stronger evidence.
Temperatures have been measured, and are shown to be increasing. These
increases in temperatures are significant and have observable effects on the
world: glaciers are shrinking, sea ice is retreating, sea levels are rising —
even cherry blossoms are blooming earlier in the year.
In the module Climate Projections, we describe how we can attempt to
predict the climate of the future. This is a doubly difficult problem, as it
involves not only physics, but, harder yet, people. What will today’s
societies do with the foreknowledge of the consequences of our actions?
The climate has become yet another natural system whose immediate fate is
connected to our own. The reader may find it either reassuring or
frightening that we hold the climate’s future in our hands.
Climate Processes; External and Internal Controls
In this module, you will explore the processes that control the climate.
Learning Objectives
After reading this module, students should be able to
e define both "climate" and "weather" and explain how the two are
related
e use the Celsius temperature scale to describe climate and weather
e discuss the role and mechanisms of the major controls on Earth's
climate using the concepts of insolation, albedo and greenhouse gases
e identify and describe the mechanisms by which major external and
internal changes to the climate (including solar output variation,
volcanoes, biological processes, changes in glacial coverage, and
meteorite impacts) operate
e know that the Earth's climate has changed greatly over its history as a
result of changes in insolation, albedo, and atmospheric composition
e describe the processes that can lead to a "Snowball Earth" using the
"positive feedback" concept, and be able to contrast the climate factors
that influenced this period of Earth's history with others, including the
dominant factors that operated during the Cretaceous
e state the major ways in which carbon dioxide is both added to and
removed from the atmosphere, and be able to describe why levels of
carbon dioxide and other greenhouse gases can be kept in balance
Introduction
The Earth's climate is continually changing. If we are to understand the
current climate and predict the climate of the future, we need to be able to
account for the processes that control the climate. One hundred million
years ago, much of North America was arid and hot, with giant sand dunes
common across the continent's interior. Six hundred and fifty million years
ago it appears that the same land mass—along with the rest of the globe—
was covered in a layer of snow and ice. What drives these enormous
changes through Earth's history? If we understand these fundamental
processes we can explain why the climate of today may also change.
In discussing climate in this chapter, we will be using degrees Celsius (°C)
as the unit of temperature measurement.
A Thermometer This
thermometer shows how the
two scales compare for typical
atmospheric temperatures. A
change of one degree Celsius (1
°C) is equivalent to a change of
one and four fifths degrees
Fahrenheit (1.8 °F). Source:
Michiel1972 at nl.wikipedia.
The Celsius scale is the standard international unit for temperature that
scientists use when discussing the climate. In the Celsius scale, water
freezes at 0 °C and boils at 100 °C. A comfortable room might be heated to
20 °C (which is equivalent to 68 °F). Temperatures can be converted from
the Celsius scale to the Fahrenheit scale with the following equation:
Equation:
9
f= 5 Ot 82
Weather describes the short term state of the atmosphere. This includes
such conditions as wind, air pressure, precipitation, humidity and
temperature. Climate describes the typical, or average, atmospheric
conditions. Weather and climate are different as the short term state is
always changing but the long-term average is not. On The 1° of January,
2011, Chicago recorded a high temperature of 6 °C; this is a measure of the
weather. Measurements of climate include the averages of the daily,
monthly, and yearly weather patterns, the seasons, and even a description of
how often extraordinary events, such as hurricanes, occur. So if we consider
the average Chicago high temperature for the 1%‘ of January (a colder 0.5
°C) or the average high temperature for the entire year (a warmer 14.5 °C)
we are comparing the city's weather with its climate. The climate is the
average of the weather.
Insolation, Albedo and Greenhouse Gases
What controls the climate? The average temperature of the Earth is about
15 °C (which is the yearly average temperature for the city of San
Francisco), so most of the Earth's water is in a liquid state. The average
temperature of Mars is about -55 °C (about the same as the average winter
temperature of the South Pole), so all of the water on the Martian surface is
frozen. This is a big difference! One reason Earth is so much hotter than
Mars is that Earth is closer to the Sun. Mars receives less than half as much
energy from the Sun per unit area as Earth does. This difference in
insolation, which is the measure of the amount of solar radiation falling on
a surface, is a very important factor in determining the climate of the Earth.
On Earth, we notice the effects of varying insolation on our climate.
Sunlight falls most directly on the equator, and only obliquely (at an angle)
on the poles. This means that the sunlight is more concentrated at the
equator. As shown in Figure Insolation Angle, the same amount of sunlight
covers twice as much area when it strikes a surface at an angle of 30°
compared to when it strikes a surface directly: the same energy is spread
more thinly, weakening its ability to warm the Earth.
1 mile
X mile
\ 30 degrees
'1 mile
2 miles
Insolation Angle Insolation is the
effect of incidence angle on sunlight
intensity. Note that the same amount
of sunlight is spread out over twice
the area when it strikes the surface at a
30-degree angle. Source: Wikipedia
As a consequence, the tropics receive about twice the insolation as the area
inside the Arctic Circle — see Figure Insolation Comparison. This
difference in energy explains why the equator has a hot climate and the
poles have a cold climate. Differences in insolation also explain the
existence of seasons. The Earth's axis is tilted at 23° compared to its orbit,
and so over the course of the year each hemisphere alternates between
directly facing the Sun and obliquely facing the Sun. When the Northern
hemisphere is most directly facing the Sun (the months of May, June and
July) insolation is thus higher, and the climate is warmer. This variation in
insolation explains why summer and winter occur (we get less energy from
the Sun in winter then we do in summer), and why the timing of the seasons
is opposite in the Southern and Northern hemispheres.
Polar Insolation
Equatorial Insolation
Insolation Comparison A cartoon of how
latitude is important in determining the
amount of insolation. The same amount of
sunlight (yellow bars) is spread out over
twice the planet's surface area when the rays
strike the Earth at an angle (compare the
length of the dark lines at the equator and at
the poles). Source: Jonathan H. Tomkin.
Figure Insolation shows both the equatorial and seasonal impacts of
insolation. High levels of insolation are shown in warm colors (red and
pink) and low levels of insolation are shown in cold colors (blue). Notice
that in January (top map) the maximum levels of insolation are in the
Southern Hemisphere, as this is when the Southern Hemisphere is most
directly facing the sun. The Arctic receives very little insolation at this time
of year, as it experiences its long polar night. The reverse is true in April
(bottom map).
April 1984-1993
Solar Insolation (kWnh/m2/day)
Insolation Average insolation over ten years
for the months of January (top) and April
(bottom). Source: Roberta DiPasquale,
Surface Meteorology and Solar Energy
and the ISCCP Project. Courtesy of NASA's
Earth Observatory.
The equator always receives plenty of sunlight, however, and has a much
higher average temperature as a consequence; compare the average
temperature of the equator with that of the poles in Figure Annual Mean
Temperature
-50 -40 -30 -20 -10 0 10 20 30
Annual Mean Temperature
Annual Mean Temperature
The Earth's average annual
temperature. Source: Robert A.
Rohde for Global Warming Art.
The level of insolation affecting Earth depends on the amount of light (or
solar radiation) emitted by the Sun. Over the current geologic period, this
is very slowly changing—solar radiation is increasing at a rate of around
10% every billion years. This change is much too slow to be noticeable to
humans. The sun also goes through an 11-year solar cycle, in which the
amount of solar radiation increases and decreases. At the solar cycle peak,
the total solar radiation is about 0.1% higher than it is at the trough.
The Earth's orbit is not perfectly circular, so sometimes the Earth is closer
to or further from the Sun than it is on average. This also changes the
amount of insolation, as the closer the Earth is to the Sun the more
concentrated the solar radiation. As we shall see in the next section, these
orbital variations have made a big difference in conditions on the Earth
during the period in which humans have inhabited it.
In addition to considering how much energy enters the Earth system via
insolation, we also need to consider how much energy leaves. The climate
of the Earth is controlled by the Earth's energy balance, which is the
movement of energy into and out of the Earth system. Energy flows into the
Earth from the Sun and flows out when it is radiated into space. The Earth's
energy balance is determined by the amount of sunlight that shines on the
Earth (the insolation) and the characteristics of the Earth's surface and
atmosphere that act to reflect, circulate and re-radiate this energy. The more
energy in the system the higher the temperature, so either increasing the
amount of energy arriving or decreasing the rate at which it leaves would
make the climate hotter.
One way to change how quickly energy exits the Earth system is to change
the reflectivity of the surface. Compare the difference in dark surface of
tilled soil (Figure Reflectivity of Earth's Surface (a)) with the blinding
brightness of snow-covered ice (Figure Reflectivity of Earth's Surface
(b)).
Reflectivity of Earth's Surface
Tilled soil. Source: Tim Hallam.
The snow surface at Dome C Station,
Antarctica Source: Stephen Hudson
The dark soil is absorbing the sun's rays and in so doing is heating the Earth
surface, while the brilliant snow is reflecting the sunlight back into space.
Albedo is a measure of how reflective a surface is. The higher the albedo
the more reflective the material: a perfectly black surface has zero albedo,
while a perfectly white surface has an albedo of 1 - it reflects 100% of the
incident light. If a planet has a high albedo, much of the radiation from the
Sun is reflected back into space, lowering the average temperature. Today,
Earth has an average albedo of just over 30%, but this value depends on
how much cloud cover there is and what covers the surface. Covering soil
with grass increases the amount of light reflected from 17% to 25%, while
adding a layer of fresh snow can increase the amount reflected to over 80%.
Figure Surface of Earth with Cloud Cover Removed is a composite
photograph of the Earth with the cloud cover removed. As you can see,
forests and oceans are dark (low albedo) while snow and deserts are bright
(high albedo).
SN nit aa
Surface of Earth with Cloud Cover
Removed The surface of the Earth with
cloud cover removed. The poles and deserts
are much brighter than the oceans and
forests. Source: NASA Goddard Space
Flight Center Image by Reto St6ckli.
Courtesy of NASA's Earth Observatory.
Changes in albedo can create a positive feedback that reinforces a change
in the climate. A positive feedback is a process which amplifies the effect of
an initial change. If the climate cools, (the initial change), snow covers
more of the surface of the land, and sea-ice covers more of the oceans.
Because snow has a higher albedo than bare ground, and ice has a higher
albedo than water, this initial cooling increases the amount of sunlight that
is reflected back into space, cooling the Earth further (the amplification, or
positive feedback). Compare the brightness of Figure Surface of Earth
with Cloud Cover Removed with a similar photo montage from February
(Figure Surface of the Earth in February with Cloud Cover Removed):
the extra snow has increased the Earth's albedo. Imagine what would
happen if the Earth produced even more snow and ice as a result of this
further cooling. The Earth would then reflect more sunlight into space,
cooling the planet further and producing yet more snow. If such a loop
continued for long enough, this process could result in the entire Earth
being covered in ice! Such a feedback loop is known as the Snowball
Earth hypothesis, and scientists have found much supporting geological
evidence. The most recent period in Earth's history when this could have
occurred was around 650 Million years ago. Positive feedbacks are often
described as "runaway" processes; once they are begun they continue
without stopping.
Surface of the Earth in February with
Cloud Cover Removed This image shows
the surface of the Earth in February (the
Northern Hemisphere winter) with cloud
cover removed. The seasonal snow cover is
brighter (and so has a higher albedo) than
the land surface it covers. Source: NASA
Goddard Space Flight Center Image by Reto
St6ckli. Courtesy of NASA's Earth
Observatory
Albedo does not explain everything, however. The Earth and the Moon both
receive the same amount of insolation. Although the Moon is only slightly
more reflective than the Earth, it is much colder. The average temperature
on Earth is 15 °C, while the Moon's average temperature is -23 °C. Why the
difference? A planet's energy balance is also regulated by its atmosphere. A
thick atmosphere can act to trap the energy from sunlight, preventing it
from escaping directly into space. Earth has an atmosphere while the Moon
does not. If the Earth did not have an atmosphere, it would have an average
temperature of -18 °C; slightly warmer than the Moon since it has a lower
albedo.
How does the atmosphere trap the energy from the Sun? Shouldn't the
Earth's atmosphere reflect as much incoming radiation as it traps? It is true
the atmosphere reflects incoming solar radiation—in fact, only around half
the insolation that strikes the top of the atmosphere reaches the Earth's
surface. The reason an atmosphere generally acts to warm a planet is that
the nature of light radiation changes as it reaches the planet's surface.
Atmospheres trap more light than they reflect.
Humans see the Earth's atmosphere as largely transparent; that is, we can
see a long way in air. This is because we see light in the visible spectrum,
which is the light radiation in the range of wavelengths the human eye is
able to perceive, and visible light is able to travel a long way through the
Earth's atmosphere before it is absorbed. Light is also transmitted in
wavelengths we can't see, such as in the infrared spectrum, which is
sometimes referred to as infrared light, heat, or thermal radiation.
Compared to visible light, infrared light cannot travel very far in the Earth's
atmosphere before it is absorbed. Solar radiation striking the Earth is largely
in the visible part of the spectrum. The surface of the Earth absorbs this
energy and re-radiates it largely in the infrared part of the spectrum. This
means that solar radiation enters the Earth in the form of visible light,
unhindered, but tries to leave in the form of infrared light, which is trapped.
Thicker atmospheres keep this infrared radiation trapped for longer, and so
warm the Earth—just like an extra blanket makes you warmer in bed.
This effect is shown in Figure Earth Atmosphere Cartoon. The visible
light radiation enters the atmosphere, and quickly exits as infrared radiation
if there is no atmosphere (top Earth). With our atmosphere (the middle
Earth), visible light enters unhindered but the infrared light is partially
reflected back to the surface, increasing the amount of energy and thus the
temperature at the Earth's surface. If the atmosphere is made thicker
(bottom Earth) the infrared radiation is trapped for longer, further warming
the planet's surface.
No Atmosphere
Standard Atmosphere
Thickened Atmosphere
Earth Atmosphere Cartoon A
cartoon of the greenhouse effect.
(Top) Visible light radiation
emitted by the sun (yellow
arrows) strikes the Earth and
reflects as infrared radiation
(orange arrow); (middle) an
atmosphere reflects some of the
infrared radiation back toward
the planet; (bottom) a thickened
atmosphere reflects greater
amounts of infrared radiation.
Source: Jonathan H. Tomkin.
The way the atmosphere acts to trap light radiation is referred to as the
greenhouse effect, and the gases that prevent the thermal radiation from
exiting the Earth system are described as greenhouse gases. The four most
important greenhouse gases in the Earth's atmosphere are water vapor,
carbon dioxide, methane, and ozone. All four are found naturally in the
Earth's atmosphere. As we will discuss in Section 4.4, however, human
activities are adding to the natural amount of carbon dioxide and methane,
and even adding new greenhouse gases, such as chlorofluorocarbon (CFC).
Earth's Changing Atmosphere
The composition of Earth's atmosphere has changed over geologic time.
The atmosphere has largely come from volcanic venting of gas from Earth's
interior (see Figure Volcanic Outgassing), but biology has also made
important changes by producing oxygen and removing carbon dioxide.
Greenhouse gases currently make up only a small fraction of the Earth's
atmosphere—99% of air consists of nitrogen and oxygen molecules.
Volcanic Outgassing The Mt. Bromo
volcano in Indonesia emitting gas into the
atmosphere. Source: Jan-Pieter Nap, taken
on July 11, 2004.
While volcanoes can warm the Earth by adding carbon dioxide to the
atmosphere, which produces a greenhouse effect, they can also cool the
Earth by injecting ash and sulfur into the atmosphere. These additions raise
the albedo of the atmosphere, allowing less sunlight to reach the surface of
the Earth. The effect lasts until the particles settle out of the atmosphere,
typically within a few years. Volcanic eruptions have impacted human
societies throughout history; the Mt. Tambora eruption in 1815 cooled the
Earth so much that snow fell during June in New England, and the more
recent Mt. Pinatubo eruption in 1991 (see Figure Mt. Pinatubo Explosion)
ejected so much sulfuric acid into the atmosphere that global temperatures
were lowered by about 0.5 °C in the following year.
Mt. Pinatubo Explosion The 1991 eruption
of Mt. Pinatubo. Source: U.S. Geological
Evidence from the geologic past indicates that similar events have caused
mass extinctions wherein a significant fraction of all species on Earth were
wiped out in a relatively short amount of time. Sustained outgassing from
continuous volcanic eruptions is thought to have produced so much ash and
aerosols that light sufficient to support photosynthesis in plants was unable
to penetrate the atmosphere, causing the food chain to collapse. The ash
particles produced by extended eruptions would also have increased the
Earth's albedo, making conditions inhospitably cool for plants and animals
adapted to a warmer environment.
Asteroid impacts can also cause the climate to suddenly cool. When large
asteroids strike the Earth, ash is ejected into the atmosphere, which
increases albedo in the same way as volcanic eruptions. Everyday clouds
(made up of water droplets) both cool and warm the Earth. They can cool
the Earth by increasing the planet's albedo, reflecting sunlight into space
before it reaches the surface. Clouds can also warm the Earth, by reflecting
infrared radiation emitted by the surface back towards the planet. Different
types of clouds, and different conditions, determine which effect
predominates. On a hot summer's day, for example, clouds cool us by
shielding us from the sun's rays, but on a winter's night a layer of cloud can
act as a warming blanket.
The composition of the Earth's atmosphere is not fixed; greenhouse gases
can be added to and removed from the atmosphere over time. For example,
carbon dioxide is added by volcanoes and the decay or burning of organic
matter. It is removed by photosynthesis in plants, when it is dissolved in the
oceans and when carbonate sediments (a type of rock) are produced. Over
geologic time, these processes have significantly reduced the proportion of
carbon dioxide in the atmosphere. Atmospheric carbon dioxide levels just
prior to the industrial revolution are thought to have been only one
twentieth of those of 500 million years ago. Natural processes also remove
carbon dioxide added by human activity, but only very slowly. It is
estimated that it would take the Earth around a thousand years to naturally
remove most of the carbon dioxide released by the industrial consumption
of fossil fuels up to the present.
Greenhouse gases other than carbon dioxide are shorter-lived: methane is
removed from the atmosphere in around a decade, and chlorofluorocarbons
break down within a century. Individual water molecules spend only a few
days at a time in the atmosphere, but unlike the other greenhouse gases, the
total amount of water vapor in the atmosphere remains constant. Water
evaporated from the oceans replaces water lost by condensation and
precipitation.
Changing the composition of the Earth's atmosphere also changes the
climate. Do you remember the Snowball Earth — how increasing ice cover
also increased the Earth's albedo, eventually covering the entire planet in
ice and snow? Today's climate is temperate—so we must have escaped this
frozen trap. But how? The leading hypothesis is that the composition of the
Earth's atmosphere changed, with volcanoes slowly adding more and more
carbon dioxide to it. Without access to the oceans, plants, or surface rocks,
this carbon dioxide was not removed from the atmosphere and so continued
to build up over millions of years. Eventually, the additional warming
caused by the increase in greenhouse gases overcame the cooling caused by
the snow's high albedo, and temperatures rose enough to melt the ice,
freeing the Earth.
For most of Earth's history, carbon dioxide concentrations have been higher
than they are today. As a consequence, past climates have often been very
warm. During the late stage of the dinosaur era (the Cretaceous, a period
that lasted between 65 and 145 million years ago), carbon dioxide levels
were about 5 times higher than they are today, and the average global
temperatures were more than 10 °C higher than today's. There were no large
ice sheets, and dinosaur fossils from this period have been found as far
north as Alaska. These animals would not survive the cold conditions found
in the arctic today. Further south, fossil crocodiles from 60 million years
ago have been found in North Dakota. The modern average winter
temperature in North Dakota is around -10 °C —but being cold-blooded,
crocodiles are most at home when the air temperature is around 30 °C! The
climate was warmer in the past when the amount of carbon dioxide was
higher.
Review Questions
Exercise:
Problem:
The text describes how the high albedo of snow acts as a positive
feedback—if the Earth is made cooler, the highly reflective snow can
act to further cool the Earth. Today, part of the Earth is covered with
snow and ice. Can you describe a mechanism by which warmer
temperatures would also produce a positive feedback—this time
heating the Earth further—through a similar albedo mechanism?
Exercise:
Problem:
Mars is colder than the Earth. Venus, on the other hand, is much hotter,
with average surface temperatures of around 450 °C. Venus is closer to
the Sun than the Earth is, and so receives about twice as much solar
radiation. Venus's atmosphere is also different than Earth's, as it is
much thicker and mainly consists of carbon dioxide. Using the terms
insolation and greenhouse gases, can you suggest reasons why Venus
is so hot?
Exercise:
Problem:
Oxygen makes up over 20% of Earth's atmosphere, while carbon
dioxide makes up less than 0.04%. Oxygen is largely transparent to
both visible and infrared light. Explain why carbon dioxide is a more
important greenhouse gas in the Earth's atmosphere than oxygen, even
though there is much more oxygen than carbon dioxide.
Exercise:
Problem:
Figure Insolation shows the insolation at the surface of the Earth. The
Earth is spherical, so we would expect the values to be the same for
places of the same latitude. But notice that this is not true — compare,
for example, central Africa with the Atlantic Ocean at the same
latitude. What feature of the atmosphere might explain this variation,
and why?
Resources
The National Aeronautical and Space Administration (NASA) Earth
Observatory website has an array of climate resources. For a more in-depth
discussion of Earth's energy budget, go to
http://earthobservatory.nasa.gov/Features/EnergyBalance/
Are you interested in finding more about the controversial Snowball Earth
hypothesis? The National Science foundation and Harvard University have
set up a website with more about the hypothesis and the evidence. Go to
http://www.snowballearth.org/
Glossary
albedo
A measure of how reflective a surface is. A perfectly black surface has
an albedo of 0, while a perfectly white surface has an albedo of 1.
climate
The average of the weather.
cretaceous period
The period between 65 and 145 million years ago, which was the final
period of Earth's history that included dinosaurs.
greenhouse effect
The process by which the atmosphere acts to trap heat, warming the
climate.
greenhouse gases
Those gases in the atmosphere that warm the climate, most
importantly, water vapor, carbon dioxide, methane, and ozone.
infrared spectrum
The light radiation just below the range of wavelengths visible to the
human eye. Also referred to as thermal radiation.
insolation
The measure of the amount of solar radiation falling on a surface.
positive feedback
A runaway process which amplifies the effect of an initial change.
snowball earth
A condition in which the entire planet is covered in ice, last thought to
have happened 650 million years ago.
solar radiation
The energy emitted by the sun in the form of light.
visible spectrum
The light radiation that is in the range of wavelengths that is visible to
the human eye.
weather
A description of the short term state of the atmosphere.
Milankovitch Cycles and the Climate of the Quaternary
In this module, we will look at the recent natural changes in Earth’s climate,
and we will use these drivers to understand why the climate has changed.
Learning Objectives
After reading this module, students should be able to
e describe the changing climate of the Quaternary
e explain why Milankovitch cycles explain the variations of climate over
the Quaternary, in terms of the similar periods of orbital variations and
glacial cycles
e explain how the glacier/climate system is linked via albedo feedbacks
e describe how sediment and ice cores provide information about past
climates
e use the mechanisms that cause stable isotope fractionation to predict
the impact of changing climate on stable isotope records
Introduction
In Module Climate Processes; External and Internal Controls we saw
the major drivers of the climate—the energy that comes from the Sun
(insolation) and the properties of the planet that determine how long that
energy stays in the Earth system (albedo, greenhouse gases). In this section,
we will look at the recent natural changes in Earth's climate, and we will
use these drivers to understand why the climate has changed.
The most recent period of Earth's geologic history—spanning the last 2.6
million years—is known as the Quaternary period. This is an important
period for us because it encompasses the entire period over which humans
have existed—our species evolved about 200,000 years ago. We will
examine how the climate has changed over this period in detail. By
understanding recent natural processes of climate change, we will be able to
better understand why scientists attribute the currently observed changes in
global climate as being the result of human activity.
Quaternary Climate — Information From Ice Cores
How do we know about the Quaternary climate? After all, most of the
period predates human existence, and we have only been recording the
conditions of climate for a few centuries. Scientists are able to make
informed judgments about the climates of the deep past by using proxy
data. Proxy data is information about the climate that accumulates through
natural phenomena. In the previous module, for example, we discussed how
60-million-year-old crocodile fossils have been found in North Dakota. This
gives us indirect information about the climate of the period—that the
climate of the region was warmer than it is today. Although not as precise
as climate data recorded by instruments (such as thermometers), proxy data
has been recovered from a diverse array of natural sources, and provides a
surprisingly precise picture of climate change through deep time.
One highly detailed record of past climate conditions has been recovered
from the great ice sheets of Greenland and Antarctica. These ice sheets are
built by snow falling on the ice surface and being covered by subsequent
snowfalls. The compressed snow is transformed into ice. It is so cold in
these polar locations that the ice doesn't melt even in the summers, so the
ice is able to build up over hundreds of thousands of years. Because the ice
at lower depths was produced by progressively earlier snowfalls, the age of
the ice increases with depth, and the youngest ice is at the surface. The
Antarctic ice sheet is up to three miles thick. It takes a long time to build up
this much ice, and the oldest ice found at the bottom of the Antarctica ice
sheet is around 800,000 years old.
Scientists drill into these ice sheets to extract ice cores, which record
information about past climates. Figure Ice Cores shows what these cores
look like when they are cut open. Like tree rings, ice cores indicate years of
growth. Note how the middle core (which required over a mile of drilling to
extract!) has distinct layers—this is because the seasons leave an imprint in
the layers of snow. Scientists can use this imprint to help calculate the age
of the ice at different depths, although the task becomes more difficult the
deeper the core sample, since the ice layers become more compressed. The
ice records several different types of climate information: the temperature
of the core, the properties of the water that make up the ice, trapped dust,
and tiny entombed bubbles of ancient atmosphere.
1836-1837 meters
3050-3051 meters
Ice Cores Three different sections of an ice core. The seasonal layers
are most clear in the middle section (note the dark and light bands).
The deepest section (bottom core) is taken from almost two miles
down and is colored brown by rocky debris from the ground under the
ice. Source: National Ice Core Laboratory
The water molecules that make up the ice record information about the
temperature of the atmosphere. Each water molecule is made up of two
hydrogen atoms and one oxygen atom (and so has the chemical name H20).
Not all oxygen atoms are the same however; some are "light" and some are
"heavy". These different types of oxygen are called isotopes, which are
atoms that have same number of protons but different numbers of neutrons.
The heavy isotope of oxygen (oxygen-18, or !8O) is more than 10% heavier
than the light isotope (oxygen-16 or '°O). This means that some water
molecules weigh more than others. This is important because lighter water
molecules are more easily evaporated from the ocean, and once in the
atmosphere, heavier water molecules are more likely to condense and fall as
precipitation. As we can see from Figure Oxygen Schematic, the water in
the ice sheets is lighter (has a higher proportion of !°O relative to ‘8O) than
the water in the oceans.
The process of differentiation between heavy and light water molecules is
temperature dependent. If the atmosphere is warm, there is more energy
available to evaporate and hold the heavier !8O water in the atmosphere, so
the snow that falls on the polar ice sheets is relatively higher in !®O. When
the atmosphere is cold, the amount of energy is less, and so less !®O makes
it to the poles to be turned into glacial ice. We can compare the amount of
‘80 in different parts of the ice core to see how the atmosphere's
temperature—the climate—has changed.
Near the poles, atmospheric water vapor
is increasingly depleted in ""O.
Heavy, "O-ich water
condenses over
mid-atitudes.
water from glacial
§ depleted in “O
Water, slightly Gepleied in “ov
we evaporates from warm sub-tropical Boters
Oxygen Schematic Water becomes lighter as it travels
toward the poles. The heavy (180) water drops out of the
atmosphere (as rain or snow) before reaching the ice
sheet. This means that the snow that forms the glacial ice
is lighter than the ocean water (has more 160 than 180,
compared to ocean water). Source: Robert Simmon,
NASA GSFC, NASA Earth Observatory
Figure Ice Age Temperature shows what this record looks like over the
last 400,000 years. The blue and green lines depict two different Antarctic
ice cores (taken from ice about 350 miles apart) and the variations in
oxygen isotopes are converted into temperature changes. The y-axis shows
temperature change; today's climate is at zero—the dashed line. Notice that
the Earth's climate has not been stable! Sometimes the temperature is higher
than it is today—the blue and green lines are higher than the dashed about
120,000 years ago, for example. Most of the time the climate is much
colder than today's, however: the most common value is around -6 °C (-13
°F). On average, the earth's temperature between 25,000 and 100,000 years
ago was about 6 °C lower than it is today. These changes can be double-
checked by measuring the temperature of the ice in the cores directly. Ice
that is 30,000 years old is indeed colder than the ice made today, just as the
isotope data predicts.
Ice Age Temperature Changes
EPICA -
Ww
T
awo
T
ATemperature (°C)
oO
too
a Ww
°
=
Ice Volume
High? 1 1 L 1 1 1 4
450 400 350 300 250 200 150 100 £50 0
Thousands of Years Ago
Ice Age Temperature The blue and green
lines depict two different Antarctic ice cores
(taken from ice about 350 miles apart) and
the variations in oxygen isotopes are
converted into temperature changes. The red
line depicts global ice volume. The y-axis
shows temperature change; today's climate
is at zero — the dashed line. Source: Robert
A. Rohde
41 kyr cycle 100 kyr cycle
Five Million Years of
Climate Change
From Sediment Cores
55 5 45 4 35 Oo «20 2 “h 1 #05 0°
Millions of Years Ago
Equivalent
Vostok AT (°C)
oOo ® KR © O WN
5'°O Benthic
Carbonate (per mil)
Five Myr Climate Change A comparison of the age of sediment (x-
axis) and the change in temperature over time (left y-axis) as derived
from oxygen isotope ratios (right y-axis). The dashed line shows
today's climate. Note that the climate is cooling over the last few
million years, but it is highly variable. In the last one million years the
climate alternates between warm and cool conditions on a 100,000-
year time scale ("100 kyr cycle"), before this it alternated on a 41,000
year cycle. Both these period lengths are the same as Milankovitch
cycles. These cores suggest that today's temperature is higher than
almost all of that of the Quaternary (the last 2.6 Million years).
Source: Jo Weber
The changes in climate recorded in ice sheets are thought to be worldwide.
The same climate changes observed in Antarctica are also found in cores
taken from Greenland, which is on the other side of the Earth. Isotope data
can also be taken from sediment cored from the ocean floor—all over the
planet—and these cores also show the same changes in climate, alternating
between cold and warm. Because ocean sediment is deposited over millions
of years, the sediment can give an indication of the climate across the whole
of the Quaternary and beyond. Figure Five Myr Climate Change shows
how temperature has changed over time (blue line), compared with today
(dashed line). The temperature has, on average, gotten colder over the
Quaternary, but it also appears to oscillate between warm and cold periods.
We'll investigate these periodic changes in the next section of this chapter.
As falling snow accumulates on the ground, tiny bubbles of air become
trapped in it. These bubbles are retained as the snow transforms to ice, and
constitute tiny samples of the ancient atmosphere that can be analyzed to
find out if the changes in temperature (as recorded in the oxygen isotopes)
are related to changes in the atmosphere. The temperature recorded by the
isotopes in the ice is directly related to the amount of carbon dioxide in the
trapped air (Figure Vostok Petit Data): the times with higher carbon
dioxide are also times of high temperature.
Falling snow also captures and entombs atmospheric dust, which is topsoil
born aloft by the wind, and which is especially prevalent during droughts.
The fact that more dust occurs in the ice accumulated during cold periods
suggests that the glacial climate was dry, as well as cold.
i variation (AT) ———
400
ppmv
my NR NY NY YW
SoS Ne 8B BD
Ss 5S 6&6 6 6
=
r=)
S
b
a
ro)
ail
: pee
a
)
508 a
2 o
on)
3S rl |
ro) 6
=< Ty |
Thousands of years ago
Vostok Petit Data These graphs depict how changes in temperature—
inferred from changes in isotope ratios (blue line)--correspond to
changes in atmospheric carbon dioxide (green line) and dust (red line)
over the last 400,000 years as recorded in an ice core extracted from
Antarctica. Carbon dioxide varies directly with temperature — the
warmer the climate the higher the carbon dioxide level. Atmospheric
dust is highest during the coolest periods (such as 25,000 and 150,000
years ago). Source: William M. Connolley produced figure using_data
from the National Oceanic and Atmospheric Administration, U.S.
Data.
Quaternary Climate — Cycling Between Glacials and
Interglacials
Ice Age Earth An artist's
impression of the Earth during
an ice age. Note that the
Northern parts of North
America and Europe (including
Canada and Scandinavia) are
entirely covered by ice-sheets.
Source: I[ttiz
During the Quaternary, the Earth has cycled between glacial periods
(sometimes referred to as "ice ages") and interglacial periods. The ice was
at its most recent extreme around 20,000 years ago in a period known as the
Last Glacial Maximum, or LGM. As we can see from the ice core record,
the Quaternary climate is usually cold (see Figure Ice Age Temperature),
with long periods of cold punctuated with shorter (10,000 year long, or so)
periods of warmer conditions, like those we experience today. In many
ways, our current climate is exceptional—for most of human existence, the
Earth has been a much colder place.
What was the Earth like during these glacial periods? Almost all the world
was cold; average temperatures were around 6 °C (-13 °F) colder than
today. Such conditions allow ice sheets to grow—much of North America,
Asia and Europe were covered under mile-thick ice (see Figure Ice Age
Earth). Because this ice was made of water that was once in the oceans, sea
levels were much lower. At the LGM, sea level was about 120 meters (or
about 400 feet) lower than it is today. As the seas retreated, the continents
grew larger, creating land bridges that joined Asia with North America,
Britain with Europe, and Australia with Papua New Guinea.
During glacial periods the climate was also much drier, as evidenced by the
increase in atmospheric dust (Figure Vostok Petit Data). The lands at and
near the poles were covered with ice, and dry grasslands occupied areas
where temperate forests occur today. Deserts were much larger than they
are now, and tropical rainforests, having less water and less warmth, were
small. The animals and plants of glacial periods were different in their
distribution than they are today, as they were adapted to these different
conditions. Fossils of Mastodons (Figure Knight Mastodon) have been
found from all across what is now the United States, including from
Florida, which currently enjoys a subtropical climate.
Knight Mastodon An artist's impression of
a Mastodon, an elephant-like mammal with
a thick wooly coat. Mastodon fossils dating
from past glacial periods have been found
across North America—from Florida to
Alaska. Source: Charles R. Knight
During glacial periods humans would have been unable to occupy the globe
as they do today because all landmasses experienced different climactic
conditions. Some countries of the present could not exist, as they would be
almost completely covered by ice. As examples, look for Canada, Iceland
and The United Kingdom in Figure 800pn Northern Icesheet.
Milankovitch Cycles
Why has the Earth cycled through hot and cold climates throughout the
Quatemary? As we learned in the previous module, the Earth's climate is
controlled by several different factors—insolation, greenhouse gases, and
albedo are all important. Scientists believe that changes in insolation are
responsible for these climate swings, and the insolation varies as a result of
wobbles in the Earth's orbit.
The Earth's orbit is not fixed — it changes regularly over time. These
periodic changes in Earth's orbit named are referred to as Milankovitch
Cycles, and are illustrated in Figure Milankovitch Cycles. Changes in the
Earth's orbit alter the pattern of insolation that the Earth receives. There are
three principle ways in which the Earth's orbit varies:
1. Eccentricity (or Orbital shape). The Earth's orbit is not perfectly
circular, but instead follows an ellipse. This means that the Earth is,
through the course of the year, sometimes closer and sometimes further
away from the Sun. Currently, the Earth is closest to the Sun in early
January, and furthest from the Sun in Early July. This changes the
amount of insolation by a few percent, so Northern Hemisphere
seasons are slightly milder than they would be if the orbital was
circular (cooler summers and warmer winters). The orbital shape
changes over time: the Earth moves between being nearly circular and
being mildly elliptical. There are two main periods over which this
change occurs, one takes around 100,000 years (this is the time over
which the orbit goes from being circular, to elliptic, and back to
circular), another takes around 400,000 years.
2. Axial Tilt (or Obliquity). The Earth axis spins at an angle to its orbit
around the Sun — currently this angle is 23.5 degrees (this angle is
known as the axial tilt). This difference in orbit creates the seasons (as
each hemisphere takes turns being tilted towards and away from the
Sun over the course of the year). If the axis of spin lined up with the
direction of the Earth's orbit (so that the tilt angle was zero) there
would be no seasons! This axial tilt also changes over time, varying
between 22.1 and 24.5 degrees. The larger the angle, the larger the
temperature difference between summer and winter. It takes about
41,000 year for the axial tilt to change from one extreme to the other,
and back again. Currently, the axial tilt is midway between the two
extremes and is decreasing—which will make the seasons weaker
(cooler summers and warmer winters) over the next 20,000 years.
3. Axial Precession. The direction of Earth's axis of rotation also
changes over time relative to the stars. Currently, the North Pole points
towards the star Polaris, but the axis of rotation cycles between
pointing to that star and the star Vega. This impacts the Earth's climate
as it determines when the seasons occur in Earth's orbit. When the axis
is pointing at Vega, the Northern Hemisphere's peak summer is in
January, not July. If this were true today, it would mean that the
Northern Hemisphere would experience more extreme seasons,
because January is when the Earth is closest to the Sun (as discussed
above in eccentricity). This cycle takes around 20,000 years to
complete.
Milankovitch Cycles
Precession
26,000 years
Eccentricity
100,000 - 413,000 years
—
\
ec
\
Tilt
41,000 years
21.5° - 24.5°
Currently 23.5°
©The COMET Program
Milankovitch Cycles Illustration of the three variables
in Earth's orbit, with periods of variation marked.
Source: COMET® at the University Corporation for
Commerce. ©1997-2009 University Corporation for
Atmospheric Research. All Rights Reserved.
The three cycles described above have different periods, all of which are
long by human standards: 20,000, 40,000, 100,000 and 400,000 years. If we
look at the temperature data from ice and sediment cores, we see that these
periods are reflected in Earth's climate. In the last million or so years, the
100,000-year eccentricity in the orbit has determined the timing of
glaciations, and before that the 40,000-year axial tilt was dominant (Figure
Five Myr Climate Change). These cycles have been important for a long
time; geologists have even found evidence of these periods in rocks that are
hundreds of millions of years old.
But how do the Milankovitch Cycles change our climate? These orbital
cycles do not have much impact on the total insolation the Earth receives:
they change only the timing of that insolation. Since the total insolation
does not change, these orbital variations have the power to make the Earth's
seasons stronger or weaker, but the average annual temperature should stay
the same. The best explanation for long term changes in average annual
temperature is that the Milankovitch cycles initiate a positive feedback that
amplifies the small change in insolation.
Insolation and the Albedo Feedback
Today, the Earth's orbit is not very eccentric (it is almost circular), but at the
beginning of each of the recent ice age periods, the orbit was much more
elliptical. This meant that the Earth was further away from the sun during
the northern hemisphere summers, reducing the total insolation. Lower
insolation meant that the summer months were milder than they would
otherwise be, with cooler temperatures. Summer temperatures were also
lower when the Earth's axial tilt was smaller, so the two different orbital
parameters could reinforce one another's effects, in this case producing
especially mild summers.
It is thought that these mild northern summers produced an albedo feedback
that made the whole planet slip into an ice age. The northern hemisphere
has continents near the poles—Europe, Asia, and North America. Today,
these continents have largely temperate climates. During the winter, snow
falls across much of the land (see Figure Surface of the Earth in February
with Cloud Cover Removed in the previous module) only to melt during
the summer months. If the summers are not hot enough to melt all the snow
and ice, glaciers can advance, covering more of the land. Because ice has a
high albedo, more sunlight is reflected than before, and the Earth is made
cooler. This creates a positive feedback, as the cooler conditions allow the
ice to advance further—which, in turn, increases the albedo and cools the
Earth! Eventually, a large proportion of the northern continents became
covered in ice (Figure 800pn Northern Icesheet).
800pn Northern Icesheet Glacial coverage (light blue)
of the northern hemisphere during the ice ages. Source:
Hannes Grobe
This positive feedback process works in the other direction, as well. The
interglacial periods are ushered in when the orbital parameters create
summers that are unusually warm, which melts some of the ice. When the
ice sheets shrink, the Earth's albedo decreases, which further warms the
system. The giant northern ice sheets shriveled up in a few thousand years
as warm summers and decreasing albedo worked together.
These cycles of alternating cooling and warming are also related to changes
in the amount of greenhouse gases in the atmosphere. As we observed in
Figure Vostok Petit Data, the climate contains higher levels of carbon
dioxide during interglacial periods. Although this appears to make sense—
carbon dioxide is a greenhouse gas, and so should produce warmer climates
—it is also a puzzle, because it is not clear how changes in Milankovitch
cycles lead to higher levels of carbon dioxide in the atmosphere. It is clear
that these changes in carbon dioxide are important in making the change in
temperature between interglacial and glacial periods so extreme. Several
different hypotheses have been proposed to explain why glacial periods
produce lower levels of carbon dioxide (it may be related to how the
physical changes influence the Earth's ecosystems ability to absorb carbon
dioxide: perhaps lower sea levels increase the nutrient supply in the ocean,
or the drop in sea level destroys coral reefs, or iron-rich dust from new
deserts fertilizes the oceans) but further work on this question remains to be
done.
It is a concern for all of us that there are gaps in our understanding of how
the feedbacks between insolation, albedo and greenhouse gases operate, as
it makes it hard to predict what the consequences of any changes in the
climate system might lead to. The current level of atmospheric carbon
dioxide is unprecedented in human experience; it is at the highest level ever
recorded in the Quaternary. Will the current increase in greenhouse gases
lead to a positive feedback, warming the Earth even more?
Review Questions
Exercise:
Problem:
In the text, we discuss how polar ice has a smaller !8O to !°O ratio
(that is, it has proportionally less heavy isotope water) than ocean
water does. Hydrogen also has isotopes, the two most common being
hydrogen-1 (‘H) and hydrogen-2 (7H, also known as deuterium). Water
is made up of both hydrogen and oxygen, and scientists analyze both
elements when examining ice cores. Do you predict that polar ice
sheets would have a higher ratio or a lower ratio of 'H to 7H than
ocean water? Will colder global temperatures increase or decrease the
amount of 7H in polar ice?
Exercise:
Problem:
In the text, we discuss how polar ice has a smaller !8O to !°O ratio
(that is, it has proportionally less heavy-isotope water) when the
climate is cooler. We also discuss how changes in the ratio of !8O to
‘60 ratio in sediment cores can also be used to determine the climate's
average temperature. In ocean sediments, the ratio of 80 to '°O
increases when the climate is cooler (that is, it has proportionally more
heavy isotope water). Explain why isotope ratios in ocean sediment
have the opposite reaction to those in polar ice.
Exercise:
Problem:
There are three different ways in which the Earth's orbit changes
through time. What combination of orbital parameters would be most
likely to start an ice age? (Hint: Ice ages require cool northern
summers. )
Resources
Do you want to know more about how ice cores are extracted and analyzed?
NASA's Earth Observatory has details about the practical issues of drilling
ice cores (deep ice needs to "relax" for as long as a year at the surface
before being cut open — or it can shatter!) and how chemical data is
interpreted. Go to
http://earthobservatory.nasa.gov/Features/Paleoclimatology_IceCores/ for
an in-depth article with great links.
Glossary
axial precession
The movement in the axis of rotation, which change in the direction of
Earth's axis of rotation relative to the stars.
axial tilt
The angle between a planet's axis of rotation and the line perpendicular
to the plane in which it orbits. The Earth's current axial tilt is 23.5
degrees.
eccentricity
A measure of how much an ellipse departs from circularity.
glacial period
A long period of time in which ice -sheets and glaciers are advanced in
their extent.
ice sheets
Glaciers big enough to cover a continent. Currently, ice sheets are
found in Antarctica and Greenland, but during glacial periods, ice
sheets have covered other land masses, including North America.
interglacial period
The warm periods of the Quaternary in which glaciers and ice-sheets
retreat. These occur between the longer glacial periods.
isotopes
Atoms that have same number of protons but different numbers of
neutrons. This means that they are the same element (e.g. oxygen),
have the same chemical properties, but different masses.
last glacial maximum
The time at which ice sheets were at their greatest extent during the
latest glacial period.
milankovitch cycles
Periodic variations in the Earth's orbit that influence its climate. These
cycles are named after Milutin Milankovitch, a mathematician who
quantified the theory.
quaternary period
The most recent geological period, spanning the time from 2.6 million
years ago to today.
obliquity
See Axial Tilt.
proxy data
Information about the climate that accumulates through natural
phenomena.
Modern Climate Change
Recent climate change, which has occurred during the modern instrument
era, is the focus of this module. It is through the lens of long-term climate
change (occurring on thousands to millions of years) that we will view
earth’s current climate and recent climate change. The goal is to investigate
how the principles listed above are shaping current climate events
Learning Objectives
After reading this module, students should be able to
e assess long-term global temperature records and place recent climate
change into the context of historical temperature observations
e explain how changes in the Sun's energy output have impacted the last
1300 years of global temperature records
e analyze the human impact on the planetary albedo and relate these
changes to recent climate change
e predict the response of the global average temperature when large
volcanic eruptions occur
e explain the enhanced greenhouse effect
e discuss how recent observations of change measured within regional
ecosystems are related to global climate change
Introduction
In previous modules, an examination of the geologic record of the earth’s
climate in the Quaternary Period revealed the primary drivers of climate
change. The most important conclusions to be drawn from the Modules
Climate Processes; External and Internal Controls and Milankovitch
Cycles and the Climate of the Quaternary are the following:
1. In the past, Earth has been significantly warmer (and mostly ice free)
and significantly colder (especially during the so-called “Snowball
Earth” eras) than it is today.
2. Climate change occurs when there are changes in insolation, albedo,
and composition of the atmosphere.
3. Climate is the average of weather, and changes to the earth’s climate
occur on long time scales.
Recent climate change, which has occurred during the modern instrument
era, is the focus of this module. It is through the lens of long-term climate
change (occurring on thousands to millions of years) that we will view
earth’s current climate and recent climate change. The goal is to investigate
how the principles listed above are shaping current climate events.
Mechanisms
Temperature Records
Figure Northern Hemisphere Surface Air clearly shows that the current
global average temperature reflects an interglacial warm period. If we focus
in on the end of this record we can observe some of the fine scale changes
in the global temperature records. Figure Northern Hemisphere Surface
Air combines proxy data (i.e., information from ice cores and tree rings)
with the modern instrument record to create a graph showing the last 1300
years of Northern Hemisphere (hereafter, NH) temperatures. Each line on
the top two panels represents a different temperature data set collected in
the NH and the bottom panel color codes the percentage of overlap among
these data sets.
1750 1800 1850 1900 1950 2000
——__ Unfiltered HadCRUT2v
CRUTEM2v
_(a) Instrumental temperatures
Temperature anomaly (°C wrt 1961-1990)
°
oO
°
Oo
0.5 ——— MBHi999 ———— MJ2003 BOS..2001 B2000 f}0.5
—— JBB..1998 ECS2002 RMO..2005 MSH..2005
——— +pw2006 ———— HCA.2006 ———— 02005 === PS2004
Instrumental
(HadCRUT2v)
nA f
MM
2
(=)
Temperature anomaly (°C wrt 1961-1990)
800 1000 1200 1400 1600 1800 2000
Temperature anomaly (°C wrt 1961-1990)
(c) Overlap of reconstructed temperatures
800 1000 1200 1400 1600 1800 2000
Year
Northern Hemisphere Surface Air Panel (a) — Northern
Hemisphere surface air temperature data from the modern
instrument era from various sources. Panel (b) — Northern
Hemisphere surface air temperature reconstruction dating back
1300 years from various sources. Panel (c) - Percent of overlap
between the various sources of Panel (b). Source: Climate Change
2007: The Physical Science Basis: Contribution of Working_Group I
to the Fourth Assessment Report of the Intergovernmental Panel on
Major features in these data include the Medieval Warm Period
approximately 1,000 years ago and the Little Ice Age approximately 400
years ago. Even with these events, the bottom panel shows that most of the
variability in the NH temperature fits within a 0.5°C temperature range.
Rarely has the temperature exceeded the 1961-1990 average, which is the
dividing line on this graph. The only major fluctuation outside of this range
is during the modern instrument era of the last 300 years, where confidence
between the data sets is high. Beginning in the 1800s, the solid black line in
each panel traces out approximately a 1°C increase in global temperatures.
It is this increase that is the central focus in recent climate change science.
Remember from the previous chapter that a 1°C change in the earth’s
temperature is a large change; reduce the global average by 4°C to 6°C and
much of the NH will be covered with ice as it was 20,000 years ago.
There has been much debate over recent climate change, especially in the
news media and among political parties around the world. This debate is
centered on the cause of the recent 1°C increase—is it a part of the natural
variability in the climate system or have anthropogenic, which simply
means human caused, influences played a major role? In a recent survey
given to more than 3,000 college students at the University of Illinois at
Urbana-Champaign, it was found the approximately two thirds of those
surveyed agreed that recent climate change was due to reasons beyond
natural variability in the climate system. (see Figure Recent Climate
Change Student Responses) Approximately 20% reported that the climate
change is due to natural changes and the remainder was undecided. Let’s
investigate both sides of this argument!
Yes, 66.9%
No, 19.6%
J
Undecided,
13.5%
Recent Climate Change Student Responses
Survey results from 3,000+ college students at the
University of Illinois at Urbana-Champaign when
asked if climate was changing beyond natural
variability. Source: Snodgrass, E.
Recall from the Module Milankovitch Cycles and the Climate of the
Quaternary that global climate will change as a response to changes in
insolation, albedo and the composition of the atmosphere. It was shown that
the amount of energy entering the earth-atmosphere system from the sun
varies less than 0.1% during the 11-year solar cycle in sunspot activity.
Outside of this cycle, the amount of energy from the sun has increased 0.12
Watts per square meter (W/m) since 1750. Is this enough excess energy
to produce the 1°C increase in global temperatures that has been observed
since the 1800s? As it turns out, the climate system needs nearly 8 times
that amount of energy to warm by 1°C. This essentially eliminates
fluctuations in solar output as the culprit for recent climate change.
Has the earth’s albedo changed since the 1800s? As we know from the
Module Climate Processes; External and Internal Controls, increases in
the Earth’s albedo lead to global cooling and decreases lead to warming.
The net effect of human existence on Earth is to brighten the surface and
increase the global albedo. This change is primarily accomplished through
intensive agriculture where forest, marshland, and open prairie are cut down
and crops like soybeans, corn, wheat, cotton, and rice are grown in their
place. Add this to the current high rates of deforestation in South America
and Africa and the evidence is clear that mankind has increased the Earth’s
albedo, which should have led to global cooling. (see Figure Deforestation
Deforestation in the Amazon (2010) Satellite image shows the
extent of deforestation in the Amazon as of 2010. Source: NASA
Outside of human influence, planetary albedo can also be changed by major
volcanic eruptions. When volcanoes erupt, they spew enormous amounts of
soot, ash, dust, sulfur, and other aerosols into the atmosphere. During major
eruptions, like that of Mt. Pinatubo in 1991, some particles of this debris
find their way into ne ane ae were they reside for a few years. (see
Figure Mt. Pinatubo Erupting in 1991) The presence of these particles
high in the earth’s atmosphere acts like a shield that prevents sunlight from
penetrating through the lower atmosphere to warm the earth’s surface.
Instead, the energy is either absorbed by the particles or reflected and
scattered away. The net effect is that large volcanic eruptions can cool the
planet for a few years by changing the earth’s albedo.
Mt. Pinatubo Erupting in 1991 Photograph of Mt. Pinatubo
erupting in the Philippines in 1991. Source: USGS/Cascades Volcano
Observatory
Observations of Solar Output and Volcanic Eruptions
At first glance the Figure Radiative Forcings & Simulated Temperatures
looks quite complicated, but let’s break this graph down to understand how
changes in the sun’s output and volcanic eruptions have contributed to
recent climate change. In the top panel (a), changes in the amount of energy,
measured in W/m?, are graphed against time to show how volcanic
eruptions have impacted the amount of energy the earth receives from the
sun. Notice that around the year 1815, when Mt. Tambora erupted, there is a
large downward spike in the plot. Now, examine the bottom panel, which
shows the NH temperatures, just as Figure Northern Hemisphere Surface
Air displayed, and see how the temperatures in the years following 1815
took a sharp downward turn. This is a direct consequence of the changes in
albedo caused by large volcanic eruptions. Next, look at the time period
between 1000 and 1300 A.D., the so-called Medieval Warm Period. In
panel (b), changes in solar output are graphed against time; notice that
during the Medieval Warm Period, the amount of insolation was high
compared to the average. The opposite occurred during the Little Ice Age
which peaked around 400 years ago.
8
i
8
8
8
38
oS
a
(2. MA) Buyos0y o}UeTI|OA,
Solar irradiance forcing (W m7”)
— — GSZ2003 —— ORB2006 —— TBC..2006 ——- AJS..2006
—— BLC..2002 ———- CBK..2003 ——— GRT..2005 —— GJB..2003
B..2003-14C —-- B..2003-10Be —-- GBZ..2006 ——- SMC2006
(c) All other forcings
(.-w mM) sBuyo10) JeuI0 liv
Overlap of reconstructed temperatures
| | |i
0 10 20 30 40 50 60 70 80 90 %
Temperature anomaly (°C wrt 1500-1899)
Radiative Forcings & Simulated Temperatures Plot (a) -
Radiative forcing due to volcanic eruptions over the last 1,300
years. Plot (b) - Radiative forcing due to fluctuations in solar
irradiance over the last 1,300 years. Plot (c) - Radiative forcing
due to all other forcing over the last 1,300 years. Plot (d) —
Northern Hemisphere temperature reconstruction with overlap
(shading) over the last 1,300 years. Source: Climate Change
2007: The Physical Science Basis: Contribution of Working
Group I to the Fourth Assessment Report of the
University Press
Alterations to the Natural Greenhouse Effect
We have ruled out the first two mechanisms (i.e., changes in albedo and
insolation) as reasons for the recent increase in global temperatures. But
when we look at panel (c) in Figure Radiative Forcings & Simulated
Temperatures, we notice that the “all other forcing” curves point to a rapid
increase in the amount of energy retained by the earth-atmosphere system
over the last 200 years. What is responsible for the increasing tail on this
graph? Have humans altered the composition of the Earth’s atmosphere to
make it more efficient at absorbing the infrared radiation that would have
otherwise been lost to space? Is there proof of a human enhancement to the
natural greenhouse effect? Can we explain the recent warming on an
anthropogenic adjustment to the greenhouse gases like carbon dioxide
(CO>)? Is an “enhanced greenhouse effect” to blame for the fact that the top
ten warmest years since the modern era of instrument measurements have
occurred since 1995, as seen in Figure Annual Global Temperature
Anomalies.
Jan-Dec Global Mean Temperature over Land & Ocean
if
1880 1900 1920 1940 1960 1980 2000
NCDC/NESDIS/NOAA
@ Anomaly (°C) relative to 1901-2000
Annual Global Temperature Anomalies Global average surface
temperature from 1880 to 2007. Source: National Climate Data
Center
Long before the term “global warming” became a common household
phrase, nineteenth-century Irish physicist John Tyndall said, “Remove for a
single summer-night the aqueous vapor from the air which overspreads this
country, and you would assuredly destroy every plant capable of being
destroyed by a freezing temperature.” This now famous quote reveals the
importance of greenhouse gases, like water vapor, in maintaining a balance
between the incident solar radiation and the emitted terrestrial radiation.
Tyndall understood that without greenhouse gases, water vapor being the
most abundant, the earth’s temperature would be markedly cooler. The
global average surface temperature is approximately 15°C (59°F) but if the
greenhouse gases were removed, the average global temperature would
plummet to -18°C (0°F). Remember that these gases make up a small
fraction of the composition of the atmosphere! Therefore, adjustments to
their concentration will produce dramatic effects.
To understand why these gases are so efficient at keeping the planet warm,
let’s examine Figure Atmospheric Transmission. The top panel of this
figure shows the normalized intensity of the radiation emitted by both the
sun and earth as a function of wavelength. The middle panel shows the total
atmospheric absorption spectrum and the bottom panel shows the individual
gas absorption spectrum (excluding Nitrogen and Argon). Notice from the
top panel that the sun’s peak energy emission falls within the visible portion
of the spectrum and suffers very little atmospheric absorption (middle
panel). The peak emission wavelength for the earth is in the thermal
infrared (IR), and it is effectively absorbed by water vapor (H20), carbon
dioxide (CO), methane (CHy) and nitrous oxide (NO>). The primary
purpose of this figure is to show that the gases in the earth’s atmosphere are
transparent to the sun’s peak energy emission (visible light) but not the
earth’s peak emission (thermal IR). It is through the absorption of the
earth’s outgoing thermal infrared radiation that the global average
temperature warms approximately 60°F over what it would be without
greenhouse gases.
Radiation Transmitted by the Atmosphere
2 1 10 70
Downgoing Solar Radiation Upgoing Thermal Radiation
70-75% Transmitted 15-30% Transmitted
Spectral Intensity
-_
Percent
of SaaS
ye
Oxygen and Ozone
Nitrous Oxide
Major Components
Rayleigh Scattering
70
0.2 1 10
Wavelength (um)
Atmospheric Transmission Top graph —
normalized spectral intensity (radiant energy)
emitted by the earth and sun as a function of
wavelength. Middle graph — total atmospheric
absorption as a function of wavelength. Bottom
graph — individual gas absorption as a function of
wavelength. Source: R.A. Rohde for Global
Warming Art Project
Are humans altering the natural greenhouse effect? Based upon our
assessment so far, this is the final mechanism by which the global climate
can be changed. Let’s look into the alteration of the chemistry and
composition of the earth’s atmosphere. First are humans increasing the
amount of water vapor, the most abundant but also weakest greenhouse gas
in the atmosphere? As the air temperature increases, the amount of water
vapor the atmosphere can hold also increases. However, a closer
investigation of the water cycle is needed to understand what will happen to
this increase in water vapor. In this cycle, the amount of evaporation must
equal the amount of condensation and thus precipitation on a global scale.
This equilibrium must be achieved or else water would end up entirely in its
liquid form or in its vapor form. Also due to the speed at which the
hydrological cycle operates, a large increase in water vapor would be
quickly precipitated out of the atmosphere.
Other greenhouse gases progress through their respective cycles much more
slowly than water. There are vast amounts of carbon and carbon dioxide in
the earth-atmosphere system. Most carbon is locked up in rocks, where it
may remain for millions of years. The carbon dioxide that is mobile,
however, is mostly found in other places: the ocean, soils, vegetation, fossil
fuels like coal, oil, and natural gas, and also in small concentrations in the
atmosphere. These reservoirs of CO can exchange mass like oceans and
clouds do in the water cycle, but with one extremely important difference—
the exchange rate is much slower. That means the system can get out of
balance and remain out of balance for a long time, hundreds or thousands of
years. There are two primary mechanisms for sequestering carbon dioxide
that is released into the atmosphere: it can be captured by the respiration of
plants, or dissolved in the ocean.
However, the rate at which plants and oceans can take CO, out of the
atmosphere is fixed. Therefore, if a surplus of CO, is added to the
atmosphere, it will stay there for a long time. This has major implications,
given the fact that CO, is a powerful greenhouse gas. The question then to
ask becomes, “is this exchange rate out of balance?”
The current average concentration of CO, in the atmosphere is about 390
parts per million (PPM), which means there are 390 parts of CO> per
million parts of air. That does not seem like very much, but if that small
amount of carbon dioxide were removed from the air, the global average
temperature would plummet. Has this concentration been changing? To
answer the question, we will turn to the findings of Richard Keeling, whose
life’s work was the observation of CO, concentrations at the Mauna Loa
Observatory in Hawaii. Beginning in the early 1950s, observations of COs,
a well-mixed gas in our atmosphere, have shown a remarkable climb in
concentration. (see Figure CO» Concentrations at the Mauna Loa
Observatory) The “Keeling Curve,” as it is sometimes called, clearly
shows that since the 1950s CO, concentrations have increased steadily from
315 ppm to 390 ppm. The zigzag nature of this graph is due to life cycle of
plants in the NH. The NH has much more land area that the SH, so when
spring and summer arrive in the NH, the abundance of new plant life
reduces the CO» concentrations in the atmosphere. When the plants die or
become dormant in the fall and winter, CO concentrations spike again.
380- i
a |
wts per million)
Co, (p<
Mauna Loa Observatory
1960 1970 1980 1990 2000
Year
CO, Concentrations at the Mauna Loa
Observatory The “Keeling Curve” of CO)
concentrations measured in Mauna Loa, Hawaii,
since the 1950s. Source: NASA Earth Observatory
What is troublesome about this figure is that the carbon cycle is out of its
normal rhythm and a surplus of CO», a known greenhouse gas, is building
in the earth’s atmosphere. Where is this surplus coming from? To answer
this question, let’s look at two historical records of CO, concentrations
taken from ice core deposits. The top panel in Figure Changes in
Greenhouse Gases from Ice Core and Modern Data shows the past
10,000 years of atmospheric CO, concentrations. Before 1750, the amount
of CO, in the atmosphere was relatively steady at 280 ppm. Since 1750
there has been a dramatic increase in CO, concentrations.
Methane (ppb) Carbon Dioxide (ppm)
Nitrous Oxide (ppb)
i
£
350 =
a
£
5
irs
@
300 =
s
co
c
250
2000
i
£
1500 =
b°))
[=]
9
©
1000 g
rs
5
co)
c
500
330 @IPCC 2007: WG1-AR4
i
£
300 =
t))
c¢
°
£
g
270 =
s
iy
c
10000 5000 0
Time (before 2005)
Changes in Greenhouse Gases
from Ice Core and Modern
Data Top panel shoes CO,
concentrations (ppm) over the
last 10,000 years. Source:
Climate Change 2007: The
Physical Science Basis:
Contribution of Working_Group
I to the Fourth Assessment
Report of the Intergovernmental
Panel on Climate Change
If we look even further back in time, over the last half million years, we see
a similar story. (see Figure Evidence of Climate Change) The current
concentration of CO, in the earth’s atmosphere is higher than at any time in
the past half million years. Where is this abundance of CO, coming from?
Which reservoirs are being depleted of their CO, while the atmosphere
takes on more? The answer lies in the burning of fossil fuels and in the
deforestation of significant chunks of the earth’s forest biomes. Notice the
spike in CO» concentrations beginning around 1750. This time period
marks the beginning of the industrial revolution, when fossil fuels overtook
wood as the primary energy source on our planet. Over the subsequent two
and a half centuries, oil, coal, and natural gas have been extracted from
their underground reservoirs and burned to generate electricity and power
modern forms of transportation. The exhaust from this process is currently
adding 30 billions of tons, or gigatons (Gt), of carbon dioxide to the
atmosphere each year. Combine this addition of CO2, a known greenhouse
gas, to the subtraction of one of the sinks of CO, through deforestation and
the imbalance grows even further.
current level ——>
c
°
&
n
~
a
N
O
400,000 350,000 300,000 250,000 200,000 150,000 100,000 50,000
YEARS before today (0 = 1950)
Evidence of Climate Change CO, concentrations over the last
400,000+ years. Source: NASA/NOAA
What is the end result? By examining the earth’s climate, both current and
past and by investigating the three ways in which climate can change, we
have arrived at the conclusion that the current warming is being caused by
an imbalance in the carbon cycle that has been induced by human activity,
namely the burning of fossil fuels. The record warmth over the last 1,300
years is very likely to have been caused by human decisions that have lead
to a change in the chemistry of the atmosphere, and which has altered the
natural climate variability toward warmer global temperatures. We are
essentially changing the climate faster and in a different direction than
natural processes have intended.
Observed Effects of Climate Change
Cherry Blossoms
In Japan each spring millions of people celebrate the blossoming of the
cherry trees to mark the arrival of warmer weather. These celebrations have
a long and storied history, and records of the cherry blossom festivals date
back more than a thousand years. In fact, the record of the timing of the
cherry blossoms in Japan is the oldest for any flowering plant! Two
scientists and historians. Richard Primack and Hiroyoshi Higuchi recently
analyzed this record and found that beginning in the early 1800s the mean
air temperature in March has slowly risen, similar to the increase shown in
Figure Northern Hemisphere Surface Air. During this same time period,
the flowering date has slowly crept earlier in the season, and the trees are
now flowering several days before they traditionally flowered. Although
urbanization of Japan has lead to an increase in temperature, recent climate
change is blamed for the earlier flowering of the Japanese cherry blossom
tree. Primack and Higuchi show how Kyoto has warmed an average of
3.4°C over the last 170 years. Climate change has contributed 18% to this
total warming in Japan and Primack and Higuchi demonstrate the
correlation of this warming with the industrial revolution.
Cherry Blossoms Photograph of cherry blossoms.
Source: Uberlemur via Wikimedia Commons
Birds, Mosquitoes, and Fire Ants
A recent article in the journal Nature discussed the response of plants and
animals to current climate change. Phenologists, scientists who study how
the periodic life cycle events of animals and plants are affected by
variations in climate over the course of seasons and years, are finding that
many species of birds are breeding and singing earlier in the year. Migrant
birds are arriving earlier, butterflies are appearing earlier and some
amphibians are spawning weeks ahead of their historical schedule. In
addition, mountain tree lines, which are controlled by air temperature, have
been advancing to higher altitudes in Europe, and Arctic shrubs are now
found in regions that were once too cold for their existence in Alaska.
While ecological changes such as these may not be threatening from a
human perspective, others are. For example, malaria-carrying mosquitoes in
Africa are now being found at altitudes that were once too cold for them,
and outbreaks of malaria are showing up in towns and villages once thought
to be out of their reach. In parts of California and Australia, fire ants are
migrating to regions that historically have been too cold to support them.
Fire Ants Photograph of fire
ants on a piece of wood.
Source: Scott Bauer of the
Agricultural Research
Service, U.S. Department of
Agriculture via Wikimedia
Commons
Mosquitos Photograph of a mosquito on
skin. Source: Centers for Disease
Control and Prevention
Impacts of Change in the Arctic and the Antarctic
The Arctic and Antarctic are the regions experiencing the most rapid
changes due to the recent warming of the earth’s atmosphere. These two
regions on Earth are a part of the cryosphere, which is defined as the part of
the Earth that is occupied by sea ice, lake ice, ice caps and permafrost.
(For a comprehensive overview of the current state of the cryosphere and an
excellent archive of data, please check out “The Cryosphere Today’) As
explained in the Module Milankovitch Cycles and the Climate of the
Quaternary, these regions are most vulnerable due to the powerful ice-
albedo effect. One amazing depiction of polar warming can be found in the
drunken forests of Siberia. Larch and spruce trees there are often seen tilted
over on their sides and growing at strange angles. Why? Because the once
continually frozen soil, or permafrost, in which they are rooted has been
melting in recent years. As the soil thaws it becomes more malleable and
the trees begin to slant as the soil beneath them sinks. Farther north, Arctic
sea ice has been decreasing both in extent and concentration. In 2007, the
smallest extent of sea ice was measured since the 1970s, and the Northwest
Passage opened for commerce and exploration. As the sea ice extent and
concentration decreases, so does the habitat of polar bears. The sea ice is a
vital part of their hunting grounds, and recent decreases of this ice have
greatly reduced their access to certain prey. In addition to sea ice reductions,
surface melt of the ice sheet on Greenland has increased in recent years,
especially along its edges. This melt has lead to large pools and streams
forming on top of this mile-thick sheet of ice. On the other side of the
world, the Larsen B ice shelf in Antarctica recently collapsed, sending a
large section of ice into the sea. This section of the Antarctic ice cap was
roughly as large as the state of Rhode Island and it had been stably attached
to the ice shelf for the past 12,000 years. Scientists are closely watching the
Antarctic ice as nearly two-thirds of the world’s fresh water resides there.
Finally, alpine glacier retreat has been observed on every continent. With
few exceptions, these glaciers have been retracting heavily since the 1960s,
and over that time period NASA reports a global loss of 8,000 cubic
kilometers of ice, which represents a what percentage reduction?
Drunken Forests of Siberia Source: NASA Science blog
Annual Sea Jce Minimum
million
square 5
km
1980. wt. “4985. 1990 1995 2000 2005
2007 Sea Ice Extent in the Arctic Source: NASA Goddard
Space Flight Center
The Oceans’ Response
Further dramatic changes brought on by recent warming have been
observed by scientists concerned with the world’s oceans. Observations of
the world’s coral reefs have revealed an alarming rate of coral bleaching
(which is not caused by chlorine). As the oceans attempt to uptake the
abundance of CO, and absorb nearly 80% of the heat added to the earth-
atmosphere system from the enhanced greenhouse effect, the waters will
inevitably warm. As these waters have warmed over the past 40 years, the
delicate ecological balance within some of the world’s coral reefs has been
upset leading to coral bleaching. Under warmer waters the rate at which the
algae, which is an important part of the coral ecosystem, undergoes
photosynthesis is too much for the coral to manage. As a result, the coral
rids itself of the algae, which leads to an exposure of the white skeleton of
the coral. Another consequence of warming oceans is an increase in sea
level. Since 1880, sea level has risen 20 cm (8 inches). The rise in sea level
is associated both with an increase in glacial melt water and in the thermal
expansion of the seawater. An interesting consequence of this rise in sea
level has been the disappearance of the long-disputed New Moore Island
between Bangladesh and India. Both countries laid claim to the shallow,
uninhabited island due to the speculation that oil reserves may lie beneath
it, but in 2010, the sea swallowed it. Scientists at the School of
Oceanographic Studies at Jadavpur University, Kolkatta, India suggest
global warming played an important part.
Coral Bleaching A part of coral that has
experienced coral bleaching. Source: NOAA
Finally, as the planet has adjusted to warmer temperatures the proliferation
of drought conditions in some regions has dramatically affected human
populations. The Sahel, for example, is a border region between the Sahara
Desert in the north of Africa and the tropical rainforests that occupy the
central part of the continent. (see Figure The Sahel in Africa) This region
is experiencing desertification as the Sahara steadily expands southward.
Since the 1970s, the amount of precipitation in this region has been steadily
below normal. The combination of over irrigation and recent climate
change has made the region uninhabitable and forced millions to relocate.
Vegetation (NDVI)
i) 0.3 06 0.9
The Sahel in Africa Source: NASA Earth
Observatory
Sahel Rainfall Index
' ' ' ' ,
1900 1910 1920 1930 1940 1960 1960 1970 1980 1990 2000
Year
The Sahel Rainfall Index Source: NASA Earth Observatory
Review Questions
Exercise:
Problem:
In Figure Northern Hemisphere Surface Air the dividing line on the
graph is the 1961-1990 average temperature. Explain the relevance of
this line to the data presented in this figure.
Exercise:
Problem:
Explain how deforestation can lead to both a warming effect and
cooling effect for global temperatures.
Exercise:
Problem:
In Figure Atmospheric Transmission, which gas is contributing the
most to the absorption of ultra-violet light? If this gas were removed
from the atmosphere, how might global temperatures respond?
Exercise:
Problem:
If the surface of the Greenland Ice Sheet continues to melt, how will
this impact the albedo of this region and what impact will this have on
the air temperature there?
Exercise:
Problem: When sea ice melts, what happens to global sea level?
References
Walther, G. R., Post, E., Convey, P., Menzel, A., Parmesan, C., Beebee, T. J
.C., et al. (2002, March 28). Ecological responses to recent climate change.
Nature, 416, 389-395. doi: 10.1038/416389a
Glossary
anthropogenic
Caused or produced by humans.
hydrological cycle
The continuous movement of water on, above and below the surface of
the earth. This cycle is dominated by the global equilibrium in
evaporation and condensation.
little ice age
A cool period in the NH, primarily in Europe from the sixteenth to the
nineteenth century.
medieval warm period
A warm period in the NH during the tenth and eleventh centuries.
northwest passage
A sea route for commerce through the Arctic Ocean north of Canada.
permafrost
Soil that has a temperature that has remained below freezing (0°C or
32°F) for at least two years.
radiative forcing
Change in net irradiance (an energy flux) measured at some boundary.
For this text the boundary is typically at the surface of the earth or the
top of atmosphere. A positive change indicates warming and a
negative change indicates cooling.
watts per square meter (W/m?)
Energy (Joules) per second moving through a surface (square meter).
A flux of energy through a surface area.
well-mixed gas
A gas that can be found at the same concentration throughout the
lower atmosphere regardless of location.
Climate Projections
In this module, we will investigate the findings of the Intergovernmental
Panel on Climate Change (IPCC) and look at future climate projections. We
will inspect these findings and analyze their impacts on a global scale.
Learning Objectives
After reading this module, students should be able to
e assess global CO, emissions and determine which countries and
regions are responsible for the greatest emissions currently and
historically
e explain the relationship between fossil fuel usage and CO, emissions
e link variables such as wealth, population, fuel imports, and
deforestation to CO, emissions
e use IPCC future climate projections to assess future global temperature
scenarios
e distinguish between weather events and climate change, and discuss
the differences between weather forecasting and climate projections
e analyze the anthropogenic impact on climate by examining climate
change without people
e assess the regional and global impacts of climate change on air
temperature and precipitation
Introduction
In the Module Modern Climate Change we discovered that the global
warming of approximately 1°C over the past 200 years was human induced
through an enhancement of the natural greenhouse effect. We learned that
the burning of fossil fuels has upset the natural carbon cycle, which has
steadily increased the amount of carbon dioxide (CO>) in the atmosphere
since the 1750s. Finally we looked at ancillary evidence of this warming to
see the immediate impact of these changes. In this module we will
investigate the findings of the Intergovernmental Panel on Climate Change
(IPCC) and look at future climate projections. We will inspect these
findings and analyze their impacts on a global scale.
Who is Responsible? Factors to Consider
In 2007, the IPCC was awarded a share of the Nobel Prize for its work in
the area of global climate change. The IPCC is organized through the
United Nations and is composed of over 3,000 scientists from around the
world who are working together to understand current climate change and
project future climate scenarios. As of 2011, the IPCC has released four
comprehensive reports, and it has concluded, “Most of the observed
increase in global average temperature since the mid-twentieth century is
very likely due to the observed increase in anthropogenic greenhouse gas
concentrations.” This widely known statement essentially means that the
probability of occurrence is greater than 90% that the current global
warming is caused by humans burning fossil fuels. In response to these
findings, the United Nations Framework Convention on Climate Change
has called for numerous international meetings in cities including Kyoto,
Bali, Copenhagen, and others where the leaders of world have gathered to
discuss strategies to mitigate this looming disaster. At these meetings,
scientists, politicians and world leaders review the current state of
knowledge about the problem and strategize for the future. This chapter will
take a large-scale view of the global challenges of climate change.
Over the past few years, China has surpassed the United States to become
the nation that emits more greenhouse gasses than any other (see Figure
CO, Emissions for the United States and China). Currently, China is
responsible for just over 25% of global CO, emissions, which are
approximately 30 Gt per year, with the United States in a close second
place. It is important to consider population when reviewing these numbers
because there are over four times as many people living in China than in the
United States. When you compare these two countries on a per capita basis,
the average U.S. citizen emits approximately 19 metric tons of CO, per year
while the average Chinese citizen emits approximately five metric tons. In
2009, the United States consumed more than double the amount oil than the
second largest consumer, China, according to the U.S. Energy Information
Administration. Topping the list in per capita CO, emissions is the oil rich
nation of Qatar. This small country located on the Persian Gulf has the
largest per capita production of oil and natural gas. It also has the world’s
highest gross domestic product (GDP) per capita. An average citizen in this
country emits nearly 60 metric tons of CO, into the atmosphere each year.
|
Million Metric Tons of CO2
Million Metric Tons of CO2
1K
Soo
So T
0-+ 7 0
"80 '82 '84 ’86 '88 90 '92 94 '96 98 00 02 '04 06 09 ’80 '82 '84 ’86 '88 '90 '92 '94 96 98 00 02 04 06 0
Year
Carbon Dioxide Emissions from Consumption Carbon Dioxide Emissions from Consumption
CO, Emissions for the United States and China CO,
emissions in millions of metric tons graphed against time
for the United States and China. Source: Snodgrass, _E.
created graphs using data from the U.S. Energy Information
Association
Rather than point the finger at individual countries, let’s examine the bigger
problem. The maps in Figure Global Influence Maps distort the size of
each country based on a certain variable, like CO, emissions, with respect
to the rest of the world. In the upper left panel, the map is based on
population, which is why China and India appear so large. The upper right
map distorts the size of the country based upon fuel imports. Notice that the
United States, much of Europe, and Japan are expanded the most, while
Africa, the Middle East, and much of South America are barely visible.
Compare these two maps with absolute wealth and carbon emissions and
the story is quite clear. The industrialized and wealthy nations are
responsible for the largest quantities of carbon emissions and fuel imports.
These societies are built on the foundation of energy production through the
consumption of fossil fuels.
The bottom two panels tell another aspect of this story. Focus first on the
graph in the lower right, which shows forest loss by country. The world’s
forest biomes are a large part of the CO, cycle and with deforestation, a
large sink for atmospheric CO; is taken away. Notice that deforestation is
most prevalent in Africa, South America, and Indonesia while the United
States is barely visible on this map. In the United States, reforestation is
practiced, but in the rainforests of the world, which are those areas in South
America, Africa, and Indonesia that are ballooned on this map,
deforestation is commonplace.
Population
oe
Absolute a :
Poverty — Z Forest Loss ~_
Global Influence Maps The variables labeled on each map are used
to distort the size of each country to show their global influence.
Source: WorldMapper, © Copyright SASI Group (University of
Sheffield) and Mark Newman (University of Michigan).
The last graph in Figure Global Influence Maps distorts each country’s
size according to poverty. Much of Asia and Africa are distorted the most,
and it is in these regions that we need to pay close attention over the
upcoming years. Many of the nations found within these countries are what
economists and politicians call “emerging economies.” Although much of
the current abundance of CO, in the atmosphere is from developed
countries such as the United States, CO» emissions from these countries are
not increasing with time according to a 2008 report from the Energy
Information Administration. In Figure Global CO) Emissions from Coal
Combustion, the world’s CO, emissions from coal combustion in billions
of metric tons are plotted against time. Notice that countries of the
Organization for Economic Co-operation and Development (OECD), which
comprises a large group of developed and industrialized nations, have not
increased their CO, emissions from coal combustion since 1990, and future
projections also reveal a flat line in CO, emissions. Compare this to the
non-OECD countries, many of which are emerging economies like China
and India, and you see that CO, emissions are set to triple in the next 25
years. There is much debate over information like this now that recent
climate change has been linked so closely to anthropogenic emission of
CO>. This debate revolves around the fact that developed nations used coal,
oil, and natural gas during a time when the impacts of CO, and climate
change were not well researched. This meant that during the time these
countries, including the United States, industrialized there were no
regulations on the emissions of CO». Now that CO> emissions have been
shown to cause global warming, pressure is being applied to these emerging
economies to regulate and control their CO, emissions. This is subject of
much of the debate at the international climate summits at Kyoto, Bali, and
Copenhagen. What is important to remember when discussing developed
countries vs. emerging economies is that the per capita emissions of CO, in
emerging economies are approximately one third of those for developed
countries.
15
History Projections
Non-OECD
10
“w
§
uv
b
3)
E
g
2
5
OECD
0 r +
1990 2000 2007 2015 2025 2035
Global CO, Emissions from Coal Combustion The world’s CO2
emissions from coal combustion in billions of metric tons are plotted
against time for OECD countries and non-OECD countries. Source:
U.S. Energy Information Administration (Oct 2008)
Climate Projections
One of the greatest obstacles climate scientists face in educating the public
on issues of climate change is time. Most people take weather and climate
to be one branch of scientific study. In reality, this could not be further from
the truth. Weather and climate are two separate fields of study that are
joined only by one definition—climate is the average of weather. It is
important to understand this statement because people—news reporters,
broadcast meteorologists, politicians, and even scientists—often make the
mistake of attributing weather events, such as Hurricane Katrina (2005), to
global climate change. Katrina was a weather event and, as such, it cannot
be said to have been caused by global climate change. Are the ingredients
for stronger hurricanes present in greater frequency now than they have
been in the past? That’s the type of question climate scientists seek to
answer, and they do so by analyzing decades worth of data. Thirty years is
the lowest value used in the denominator of climate calculations. In other
words, 30 years is the shortest time period over which weather can be
averaged to extract climate information. Therefore, it is impossible to blame
a single weather event on climate change—this branch of science does not
work that way.
To better understand the differences between weather and climate, take a
look at Figure High Temperature vs. Low Temperature, Champaign, IL
which shows in red the actual high temperatures for each day in 2005 in
Champaign, Illinois, compared to the average high temperature in black
over a period beginning in 1899 and ending in 2009. It is completely
normal for the temperature to vary +20°F around this average. In 2005 there
were only a handful of days where the actual high was the same as the
average high. This graph shows the highly variable and chaotic behavior of
weather. But, when data from a long span of time is averaged, the
climatological mean emerges.
2005 High Temperature vs. Average Temperature (1899-2009)
Champaign, Illinois
Temperature (°F)
10 ~ ~——2005 High Temperature
—Average High Temperaure
High Temperature vs. Low Temperature,
Champaign, IL The average high temperature for
Champaign-Urbana Illinois in black (1899-2009).
The 2005 actual high temperature are graphed in
red. Source: E. Snodgrass using data from the
National Climate Data Center
To think of it another way, imagine you are in a large lecture hall with over
300 college students. If the professor were to call out one student and try to
predict the course of her life over the next 70 years it would be nearly
impossible! It would even be difficult to predict when that person would eat
her next meal. However, the professor could project with great confidence
that on average, most of the people in the room will eat dinner at 6:30PM
on a given night. Beyond this meal, most of them will graduate from
college by the time they are 22 years old. Many will be married by 27 years
old and have their first children at 30. Most will have a job by the time they
are 24 and most will have a job they like by 34. Most will have a total of
2.1 children by the time they are 36, and by the time they are 50 most will
have gone to the doctor to have their first routine procedure. Most will
retire at 67, and since they are college grads in the United States, there is a
safe bet that they will retire with over a million dollars in assets. On
average, the men in the room will die at 85 years old and most of the
women will die before their ninetieth birthday. Now, if the professor were to
single out one individual, the chances that her life would follow this path
exactly are small, but when an entire class of 300 is averaged, this is the
result. Weather is like the individual life. Climate is like the average of 300
lives. Weather and Climate are two separate branches of study in
atmospheric science.
In addition to keeping in mind the difference between weather and climate,
remember that the focus of this chapter is global climate change. It is
tempting to forget the global nature of this problem because it is happening
very slowly on a large scale and it is averaged over long time periods.
Recall the differences between weather and climate and remember that in
conjunction with global warming there can still be weather events that take
temperatures far below normal. The temptation during these events is to
discount the science behind global climate change. For example, during the
winter of 2009-2010, the weather patterns were such that the east coast of
the United States experienced repeated record-setting snowstorms and cold
air outbreaks. Many television news reports, weather broadcasts, and
newspaper headlines scoffed at the idea of global warming during this
winter and proclaimed that it was not happening or that it was a hoax. The
shortsightedness of such responses is evidenced by the fact that globally,
2009 and 2010 were among the warmest years during the instrument record:
2009 ranked seventh, and 2010 tied for first. These were likely two of the
warmest years of the last 1,300.
Climate Modeling and Future Climate Predictions
Sometimes people discount climate predictions based on their
understanding of weather predictions. They will say something like,
“Meteorologists can’t even give me a reliable forecast of the weather over
the next three days, how am I supposed to trust them to give me the forecast
for the next 100 years.” You’re not! Climate scientists do not use weather
forecast models to forecast climate conditions 100 years in advance. The
computer models that are used to predict the weather over the next few days
are entirely different from those used to predict the climate. Instead of
predicting the highly chaotic nature of temperature, precipitation, and other
common weather variables at very high spatial and temporal resolution,
climate models forecast changes in the flux of energy between earth and its
atmosphere and space. These two computer-modeling techniques differ
substantially in their computational expense as well. Although weather
forecast models are run on extremely fast computer systems at the National
Center for Environmental Prediction, the fastest computers in the world,
like the Earth Simulator in Japan and Blue Waters at the University of
Illinois at ivan -Champaign are oa with climate simulations (see
nputi hg
Petascale Computing Facility The petascale computing facility
“Blue Waters” located at the pena ie ae ok at oe
Champaign. Source: HorsePunchKid via Wikim n
What are these climate models predicting will happen by the year 2100?
First, we will look at the global average surface temperature projections.
Figure Climate Simulation Scenarios plots global surface warming against
time with the present day in the middle of this chart. Recall that over the
last 200 years, there has been a 1°C increase in global temperatures, and
that the rate of change has been extremely fast compared to natural changes
in the earth’s climate. The graphs in Figure Climate Simulation Scenarios
show the range of model projections from different climate simulation
scenarios based upon various greenhouse gas emission scenarios (left
graph). Focus on the top and bottom curves in the right panel, which show
the most dramatic warming and the most conservative warming. The worst-
case scenario, found in the top line, shows the “business as usual”
projections. If nothing is done to mitigate the emission of greenhouse gases
into the atmosphere, these climate models are predicting a 4°C to 6°C
increase in global average temperature by 2100. The best-case scenario,
from a climate change perspective, would be for a cessation of CO>
emissions or for the current emission rates to not increase. In this case, there
would still be a warming of 0.5° to 2°C by 2100 as indicated by the bottom
curves.
post-SRES (max) /
2
°
MM post-SRES range (80%)
=
~ _ 5.0 == AIT
a == AiB
8 2 40 =
© 120 E — AIFi
@ § 3.0
c w= Year 2000 constant
100 8 concentrations
2 = 2.0 = 20" centu
§ 80 5 -
ro)
3 60 8 1.0
B sol -
$ 5 0
- 20
-1.0
fe)
2000 2100 1900
Year
Climate Simulation Scenarios Left — multiple climate
model projections (or scenarios) of greenhouse gas
emissions (including CO2, CH4 and N2O) emissions in
Gt-CO2-equivalent through 2100. Right — multiple
climate model projections of globally averaged surface
air temperature through 2100. Source: Climate Change
2007: Synthesis Report, Contribution of Working Groups
I, II and III to the Fourth Assessment Report of the
Intergovernmental Panel on Climate Change, IPCC,
figures 3.1 and 3.2, pages 44 and 46.
In addition to predicting warming of the atmosphere, climate models also
suggest that sea level will continue to rise. Since 1880, sea level has risen
20 cm (approximately 8 inches) as seen in Figure Sea Levels since 1880.
This rise has been primarily the result of the water thermally expanding as it
warms along with the atmosphere. Polar ice cap melt from land-based ice
sheets and glaciers has also added to increase in sea level. The current
projection is that sea level will rise at the rate of at least 2 mm per year over
the next century, with an overall increase ranging from 15 to 60 inches cm.
Sea level (mm)
1
_
=
5
1880 1900 1920 1940 1960 1980 2000
year
Sea Levels since 1880 Measured sea level rise since
1880. The different colors represent different data sets
used to make this graph. Source: Climate Change
2007: The Physical Science Basis: Contribution of
the Intergovernmental Panel on Climate Change, |
Cambridge University Press, figure 5.13, page 410
How much confidence can we place in predictions about temperature and
sea level by climate scientists? Let’s take a little detour before we address
this important question directly. Imagine you are contemplating signing up
with a psychic so you can better plan for the future—why save for
retirement if money is tight and you’re not sure how long you’|I live? But
you are uncertain about whether she can really see what lies ahead. You
could pay her $20 a week for her predictions, and discover over time
whether they come true or not. The trouble is, during this trial period you
wouldn’t know whether to spend your money as fast as you make it or put
some aside. But you come up with a better plan. You’!l pay the psychic $20
one time, but instead of asking her to predict your future, you’ ll ask her to
tell what has happened to you in the past week. If she gets that right, she
gets your business.
Along similar lines, climate scientists assess the trustworthiness of their
models by checking how well they “predict” the past. In Figure Model
Simulations, 58 different climate model simulations were tasked with
predicting the past climate from 1900 to 2005. By comparing the model
simulations to the observed temperature record the scientists with the IPCC
tested the accuracy of their models. In Figure Model Simulations, the
yellow lines in the top panel trace out the individual model simulations, the
red line shows the model ensemble mean, and the black line represents the
actual observed mean temperature. The models performed exceedingly
well, as evidenced by the very small variability around the observed
temperature. The success of this test demonstrates the high-quality
construction of these models and shows they are capable of accurately
projecting the earth’s future climate.
Temperature anomaly ((C) ©
Temperature anomaly ((C) &
Pinatubo
Santa Maria Agung EF! Chichon
-1.0
1900 1920 1940 1960 1980 2000
Year
1.0
0.5
-1.0
1900 1920 1940 1960 1980 2000
Year
Model Simulations Top panel -
Climate model simulations of the
global mean surface temperature
compared to the observed global
mean surface temperature in black.
Each yellow line is one of 58 climate
model simulations of which the red
line is the ensemble mean. Bottom
panel — 19 climate model simulations
in blue with the ensemble mean in
dark blue. These simulations were
run without anthropogenic
influences. The thick black line is the
observed global mean surface
temperature. For a description of
each scenario, please click here.
Source: Climate Change 2007: The
Physical Science Basis: Contribution
of Working_Group I to the Fourth
Assessment Report of the
Intergovernmental Panel on Climate
Press, figure 9.5, page 684
The bottom of Figure Model Simulations and Figure Global Surface
Temperature Comparisons presents the most compelling argument that
current climate change is caused in large part by humans. The bottom panel
of Figure Model Simulations shows 19 climate model simulations between
1900 and 2000 with human influences left out of the simulations. The thick
black line represents the observed global mean surface temperature over
this time. Compare this figure with that of Figure Global Surface
Temperature Comparisons, which depicts a series of graphs that plot
temperature anomalies against time from the early 1900s to 2000. The blue
color shading on these graphs shows the computer model projections
without anthropogenic effects, while the pink shading includes them. The
black line represents the actual measured air temperatures in each of the
locations over which the inlaid graphs are positioned. Notice that without
humans the blue shading stays level or decreases with time. Compared with
the pink shading and the black line, which both increase with time, and we
find that these climate simulations cannot accurately represent the past
climate without anthropogenic effects. Simply put, these models are unable
to represent our current climate without greenhouse contributions from
humans. Rigorous testing like this proves these models are robust and well-
designed to simulate future climate conditions.
ee eee
Year
Sse models using only natural forcings ——— observations
models using both natural and anthropogenic forcings GPCG 20s: WOT
Global Surface Temperature Comparisons Comparison of
regional and global scale surface temperature 1900-2000. Pink
shading indicates the model predicted surface temperature using
only natural forcings. The blue indicates model predicted surface
temperature using natural and anthropogenic forcings. The black
lines represent the actual observations. Source: Climate Change
2007: The Physical Science Basis: Contribution of Working_Group
I to the Fourth Assessment Report of the Intergovernmental Panel
on Climate Change, Cambridge University Press, FAQ 9.2, figure
1, page 121
The IPCC began its work in the early 1990’s and they have released four
reports on climate and climate change. In each report they have included
evidence as shown in the sections above. Since a few decades have passed
since their initial reports, we can compare the actual changes since 1990 to
the IPCC forecasts. Figure Observed Temperatures vs. Projected
Temperatures compares the observed global average surface temperature
to each of the first three reports (the fourth was released in 2007). This
figure reveals that both the second (SAR) and third (TAR) reports have
been conservative in the projection of globally averaged temperature. It also
shows that the observed warming has fallen into the range of expected
warming by the IPCC. Due to their success in accurately predicting changes
in earth’s climate over this time period, the entire body of scientists shared a
part of the 2007 Nobel Prize.
Observed Temperatures vs. Projected
Temperatures Observed global average
surface temperatures (black line) overlaid on
the temperature projections of the first IPCC
report (FAR), second report (SAR) and third
report (TAR). Source: Climate Change 2007:
The Physical Science Basis: Contribution of
Working Group I to the Fourth Assessment
Report of the Intergovernmental Panel on
figure 1.1, page 98
Global Impacts of Climate Change
Globally, an increase of between 2°C and 6°C in mean surface temperature
is expected by the year 2100. Regionally, these values may differ
substantially, and some locations may actually cool over the next century.
The hardest hit locations will be the in the high northerly latitudes of the
Arctic. Figure Projected Temperature Increases depicts the variation in
expected increases in surface air temperature for the time period of 2020-
2029 and 2090-2099 with color shading. Notice that in all of these images,
the greatest changes are expected to occur at high northerly latitudes. If
these projections hold true, ice and snow cover will continue to retreat and
enhance the ice-albedo effect discussed in Module Climate Processes;
External and Internal Controls. Since the 1980s, NH snow-covered area
has shrunk by 3 million square kilometers, and many northerly lakes are
spending less time each year covered in ice.
2020 - 2029 2090 - 2099
Relative Probability Relative Probability
Relative Probability
0
-1 0 1 2 3 4 5 6 7 68
Global Average Surface Temperature Change (°C) 005115225335 445555 665 7 7.5
(°C)
Projected Temperature Increases IPCC projected temperature
increases for the years 2020-2029 and 2090-2099. Source: Climate
Change 2007: The Physical Science Basis: Contribution of Working
Panel on Climate Change, Cambridge University Press, figure SPM.6,
page15
Aside from air temperature, global precipitation patterns and amounts are
expected to change. As the atmosphere warms, its ability to hold water
vapor increases, which leads to more evaporation from water on the earth’s
surface. As this water condenses in the earth’s atmosphere to form clouds
and precipitation, the distribution of the precipitation will vary greatly.
Current projections forecast an increase in precipitation in the tropics and
polar latitudes, with drier conditions over the mid-latitudes. Even though
there will be more water vapor in the atmosphere, the distribution of
precipitation may be such that large regions formerly unused to drought
may be subjected to prolonged dry periods. Focus on the middle panels of
Figure Winter and Summer Precipitation Anomalies, which shows the
winter (top) and summer (bottom) precipitation anomalies. Notice that the
tropics and polar regions are expected to have above normal precipitation,
while the mid-latitudes have below normal precipitation. Although more
areas are expected to experience prolonged drought, these projections
suggest that when it does rain, rainfall will arrive in much greater amounts
over shorter time periods. This will lead to increased flash flooding, the
deadliest weather phenomenon in the United States.
("C) a) a, say)
005115225335445555665775 08 06 04 02 0 02 04 06 08
("C) a Os day’) (hPa)
00511522533544555566577.5 O08 -06 04-02 0 02 04 06 08 43 2 +440 1 2 3 4
Winter and Summer Precipitation Anomalies Global temperature
and precipitation projections for 2080-2099 using the A1B scenario.
Top panels are temperature (left), precipitation (middle) and sea level
pressure (right) for December-January-February. Bottom panels show
the same variables for June-July-August. Source: Climate Change
2007: The Physical Science Basis: Contribution of Working Group I
to the Fourth Assessment Report of the Intergovernmental Panel on
Climate Change, Cambridge University Press, figure 10.9, page 767
The goal of climate science is not to craft public policy on global warming.
It is to provide the public and policymakers alike with reasonable
projections about future climate conditions. This information should be
used to show the potential impacts of our presence on the climate system so
as to form the best possible mitigation plans. Current projections show that
if we are able to slow greenhouse gas emissions, the climate system will
respond with the least amount of warming. They also suggest that if we
continue with "business as usual" the change in the global climate will be
great in magnitude and occur very quickly—both beyond past "natural"
change.
Review Questions
Exercise:
Problem:
How much CO» does the average world citizen release each year into
the atmosphere? Assume a population of 7 billion people. Compare
this number to the United States, China and Qatar.
Exercise:
Problem:
Explain why the April 2011 tornado outbreak, which set the record for
the most tornadoes in a singe 24-hour period, cannot be blamed on
climate change.
Exercise:
Problem:
In Illinois, during the summer of 2009 only two days topped 90°F. In
total it was the seventh coolest summer on record. Does this disprove
climate change? In what context should we view this cold summer in
Illinois?
Exercise:
Problem:
Why will there still be global warming if there is a complete cessation
of CO, emissions?
Exercise:
Problem:
Carbon cap and trade is one of many solutions proposed to reduce
CO2 emissions. Make a list of pros and cons to a federally mandated
cap and trade system. Be sure to consider what will happen to
consumers, businesses and the federal government.
Resources
For further reading on global climate change, read A Rough Guide to
Climate Change: The Symptoms, The Science, The Solutions, by Robert
Henson (Penguin, 2011, ISBN-13: 978-1843537113)
For more information about the:
U.S. Global Change Research Program, visit
http://www. globalchange.gov/publications/reports/scientific-
assessments/us-impacts
Global temperatures in the year 2010, visit
http://www. yaleclimatemediaforum.org/2011/02/global-temperature-in-
2010-hottest-year/
Biosphere — Chapter Introduction
In this module, the Chapter Biosphere is introduced.
Introduction
Humanity and the natural world are inextricably linked. A growing
appreciation for the importance of this fact led to the formation and
publication of the Millennium Ecosystem Assessment by the United
Nations in 2005. It defines key concepts necessary for understanding how
sustainable development can be achieved. In the terms of the Assessment,
an ecosystem is a dynamic complex of plant, animal, and microorganism
communities and the nonliving environment interacting as a functional unit,
while ecosystem services are “the benefits people obtain from ecosystems.”
Ecosystem services are critical to human well-being and sufficiently diverse
and numerous to justify classification into four major categories (see Figure
harvested by us from the natural world to meet our resource needs, e.g.
food, water, timber, and fiber. Regulating ecosystem services are processes
in the Earth system that control key physical and biological elements of our
environment, e.g. climate regulation, flood regulation, disease regulation,
water purification. Cultural ecosystem services reflect the aesthetic and
spiritual values we place on nature, as well as the educational and
recreational activities dependent on ecosystems. Finally, supporting
ecosystem services are the biogeochemical cycles, as well as biological and
physical processes that drive ecosystem function, e.g. soil formation,
nutrient cycling, and photosynthesis.
CONSTITUENTS OF WELL-BEING
ECOSYSTEM SERVICES Security
epee = PERSONAL SAFETY
Provisioning = SECURE RESOURCE ACCESS
= FOOD = SECURITY FROM DISASTERS
= FRESH WATER
= WOOD AND FIBER
© FUEL
ao. Basic material
for good life Freedom
" = ADEQUATE LIVELIHOODS of choice
Supporting Regulating Bed ree ME ts ep and action
= CLIMATE REGULATION S
seurmiecreune | 5 loop ecuuaon *AGEESS TO 60008 es
= PRIMARY PRODUCTION = ™ Viifce SoBcaTion WHAT AN INDIVIDUAL
ries Health VALUES DOING
wHENGTH AND BEING
© FEELING WELL
Cultural = ACCESS TO CLEAN AIR
= AESTHETIC AND WATER
= SPIRITUAL
= EDUCATIONAL
= RECREATIONAL Good social relations
as = SOCIAL COHESION
= MUTUAL RESPECT
© ABILITY TO HELP OTHERS
LIFE ON EARTH - BIODIVERSITY
Source: Millennium Ecosystem Assessment
ARROW’S COLOR ARROW’S WIDTH
Potential for mediation by _ Intensity of linkages between ecosystem
socioeconomic factors services and human well-being
~ Low =—— Weak
(8 Medium = Medium
ME High [—] Strong
Ecosystem Services. Figure shows the linkages between
ecosystem services and human well-being. Source:
Millennium Ecosystem Assessment, 2005. Ecosystems and
Human Well-being: Synthesis. Island Press, Washington,
DG.
We benefit from the services associated with both pristine, natural
ecosystems, such as tropical rain forests or arctic tundra, and highly
managed ecosystems, such as crop fields or urban landscapes. In all cases,
ecosystems contribute to human well-being by influencing the attainability
of basic material needs (e.g. food and shelter), health (e.g. clean air and
water), good social relations and security (i.e. sufficient resources to avoid
conflict, tolerate natural and man-made disasters, provide for children, and
maintain social cohesion), as well as freedom of choice and action (an
inherent component of the other elements of well-being is the right to live
as one chooses). Linkages between some ecosystem services and human
well-being vary in strength depending on socio-economic status (See Figure
Ecosystem Services). For example, many people in developed countries
can always afford to buy imported food without dependence on the yields of
locally grown crops, thereby avoiding shortages when yields are low
because of bad weather. However, in other cases our ability to control the
impact of losing an ecosystem service on human well-being is limited. For
example, despite major engineering efforts flooding still causes
considerable human and economic damage in developed countries.
The challenge of sustainable development stems from the need to benefit
from and manage ecosystem services without causing damage to the
ecosystems and Earth system that will reduce their value in the longer term.
People have long recognized that some ways of using natural resources are
unsustainable, especially where ecosystems are rapidly exploited to the
maximum extent possible and further access to the ecosystem services can
be achieved only by moving on to previously unexploited areas, as in the
case of slash and burn agriculture. Only more recently have we come to
appreciate that human activity is altering global-scale phenomena, such as
climate regulation, and this understanding raises a host of difficult
questions. That is because the benefit of an ecosystem service may be
realized by people in one locale, while the costs (in the form of negative
environmental consequences) are imposed on people who live elsewhere,
and who may be less equipped to withstand them.
The following sections discuss: (1) the natural biogeochemical cycling of
carbon, water and nitrogen, the ecosystem services we derive from these
biogeochemical cycles and human activities that are disturbing them; (2)
species extinctions and ecosystem changes being caused by human activity;
and (3) soil, how it is formed, its value to society, and practices that
diminish or degrade it.
Glossary
Cultural Ecosystem Services
The aesthetic and spiritual values we place on nature as well as the
educational and recreational activities dependent on ecosystems.
Ecosystem
A dynamic complex of plant, animal, and microorganism communities
and the nonliving environment interacting as a functional unit.
Ecosystem Services
The benefits people obtain from ecosystems.
Provisioning Ecosystem Services
Aspects of the natural world used by us to meet our resource needs,
e.g. food, water, timber, and fiber.
Regulating Ecosystem Services
Processes in the Earth system that control key physical and biological
elements of our environment, e.g. climate regulation, flood regulation,
disease regulation, water purification.
Supporting Ecosystem Services
The biogeochemical cycles, as well as biological and physical
processes that drive ecosystem function, e.g. soil formation, nutrient
cycling, and photosynthesis.
Biogeochemical Cycles and the Flow of Energy in the Earth System
In this module, the following topics will be covered: 1) biogeochemical
cycle, 2) the natural cycles of carbon, water, and nitrogen, and 3) important
ways human activity disrupts those cycles.
Learning Objectives
After reading this module, students should be able to
e explain the concept of a biogeochemical cycle, incorporating the terms
"pool" and "flux"
e describe the natural cycles of carbon, water, and nitrogen
e name some of the important ways human activity disrupts those cycles
Introduction
If people are to live sustainably, they will need to understand the processes
that control the availability and stability of the ecosystem services on which
their well-being depends. Chief among these processes are the
biogeochemical cycles that describehow chemical elements (e.g. nitrogen,
carbon) or molecules (e.g. water) are transformed and stored by both
physical and biological components of the Earth system. Storage occurs in
pools, which are amounts of material that share some common
characteristic and are relatively uniform in nature, e.g. the pool of carbon
found as carbon dioxide (CO>) in the atmosphere. Transformations or flows
of materials from one pool to another in the cycle are described as fluxes;
for example, the movement of water from the soil to the atmosphere
resulting from evaporation is a flux. Physical components of the earth
system are nonliving factors such as rocks, minerals, water, climate, air, and
energy. Biological components of the earth system include all living
organisms, e.g. plants, animals and microbes. Both the physical and
biological components of the earth system have varied over geological time.
Some landmark changes include the colonization of the land by plants
(~400 million years ago), the evolution of mammals (~200 million years
ago), the evolution of modern humans (~200 thousand years ago) and the
end of the last ice age (~10 thousand years ago). The earth system and its
biogeochemical cycles were relatively stable from the end of the last ice age
until the Industrial Revolution of the eighteenth and nineteenth centuries
initiated a significant and ongoing rise in human population and activity.
Today, anthropogenic (human) activities are altering all major ecosystems
and the biogeochemical cycles they drive. Many chemical elements and
molecules are critical to life on earth, but the biogeochemical cycling of
carbon, water, and nitrogen are most critical to human well-being and the
natural world.
The Natural Carbon Cycle
Most of the carbon on Earth is stored in sedimentary rocks and does not
play a significant role in the carbon cycle on the timescale of decades to
centuries. The atmospheric pool of COs is smaller [containing 800 GtC
(gigatonnes of carbon) = 800,000,000,000 tonnes] but is very important
because it is a greenhouse gas. The sun emits short-wave radiation that
passes through the atmosphere, is absorbed by the Earth, and re-emitted as
long-wave radiation. Greenhouse gases in the atmosphere absorb this long-
wave radiation causing them, and the atmosphere, to warm. The retention of
heat in the atmosphere increases and stabilizes the average temperature,
making Earth habitable for life. More than a quarter of the atmospheric CO,
pool is absorbed each year through the process of photosynthesis by a
combination of plants on land (120 GtC) and at sea (90 GtC).
Photosynthesis is the process in which plants use energy from sunlight to
combine CO, from the atmosphere with water to make sugars, and in turn
build biomass. Almost as much carbon is stored in terrestrial plant biomass
(550 GtC) as in the atmospheric CO, pool. On land, biomass that has been
incorporated into soil forms a relatively large pool (2300 GtC). At sea, the
phytoplankton that perform photosynthesis sink after they die, transporting
organic carbon to deeper layers that then either are preserved in ocean
sediments or decomposed into a very large dissolved inorganic carbon pool
(37,000 GtC). Plants are called primary producers because they are the
primary entry point of carbon into the biosphere. In other words, almost all
animals and microbes depend either directly or indirectly on plants as a
source of carbon for energy and growth. All organisms, including plants,
release CO, to the atmosphere as a by-product of generating energy and
synthesizing biomass through the process of respiration. The natural
carbon cycle is balanced on both land and at sea, with plant respiration and
microbial respiration (much of it associated with decomposition, or rotting
of dead organisms) releasing the same amount of CO, as is removed from
the atmosphere through photosynthesis.
sphere tmospheric
(800) Carbon Net
12055 ; Annual Increase GtC/y: Gigatons
: " 4 of carbon/year
Photosynthesis rn
9
* 7 5 ae
** Sa Fossil fuels,
cement, and
land;use
Net terrestrial
uptake
—
3 Microbi , he lankton #
esp anc photosynthesis |
5 - a sas — —
decomposition =
Soil
(2300) Net ocean
uptake
~ Deep ocean
(37,000)
Fossil pool
(10,000) Reactive sediments
(6000)
The Carbon Cycle. Figure illustrates the carbon cycle on, above, and
below the Earth's surface. Source: |
Human Interactions with The Carbon Cycle
The global carbon cycle contributes substantially to the provisioning
ecosystem services upon which humans depend. We harvest approximately
25% of the total plant biomass that is produced each year on the land
surface to supply food, fuel wood and fiber from croplands, pastures and
forests. In addition, the global carbon cycle plays a key role in regulating
ecosystem services because it significantly influences climate via its effects
on atmospheric CO, concentrations. Atmospheric CO, concentration
increased from 280 parts per million (ppm) to 390 ppm between the start of
industrial revolution in the late eighteenth century and 2010. This reflected
a new flux in the global carbon cycle —anthropogenic CO2 emissions—
where humans release CO> into the atmosphere by burning fossil fuels and
changing land use. Fossil fuel burning takes carbon from coal, gas, and oil
reserves, where it would be otherwise stored on very long time scales, and
introduces it into the active carbon cycle. Land use change releases carbon
from soil and plant biomass pools into the atmosphere, particularly through
the process of deforestation for wood extraction or conversion of land to
agriculture. In 2009, the additional flux of carbon into the atmosphere from
anthropogenic sources was estimated to be 9 GtC—a significant disturbance
to the natural carbon cycle that had been in balance for several thousand
years previously. Slightly more than half of this anthropogenic CO, is
currently being absorbed by greater photosynthesis by plants on land and at
sea (5 GtC). However, that means 4 GtC is being added to the atmospheric
pool each year and, while total emissions are increasing, the proportion
absorbed by photosynthesis and stored on land and in the oceans is
declining (Le Quere et al., 2009). Rising atmospheric CO, concentrations in
the twentieth century caused increases in temperature and started to alter
other aspects of the global environment. Global environmental change has
already caused a measurable decrease in the global harvest of certain crops.
The scale and range of impacts from global environmental change of
natural and agricultural ecosystems is projected to increase over the twenty-
first century, and will pose a major challenge to human well-being.
The Natural Water Cycle
The vast majority of water on Earth is saline (salty) and stored in the
oceans. Meanwhile, most of the world's fresh water is in the form of ice,
snow, and groundwater. This means a significant fraction of the water pool
is largely isolated from the water cycle. The major long-term stores of fresh
water include ice sheets in Antarctica and Greenland, as well as
groundwater pools that were filled during wetter periods of past geological
history. In contrast, the water stored in rivers, lakes, and ocean surface is
relatively rapidly cycled as it evaporates into the atmosphere and then falls
back to the surface as precipitation. The atmospheric pool of water turns
over most rapidly because it is small compared to the other pools (e.g.
<15% of the freshwater lake pool). Evaporation is the process whereby
water is converted from a liquid into a vapor as a result of absorbing energy
(usually from solar radiation). Evaporation from vegetated land is referred
to as evapotranspiration because it includes water transpired by plants, i.e.
water taken up from the soil by roots, transported to leaves and evaporated
from leaf surfaces into the atmosphere via stomatal pores. Precipitation is
the conversion of atmospheric water from vapor into liquid (rain) or solid
forms (snow, hail) that then fall to Earth's surface. Some water from
precipitation moves over the land surface by surface runoff and
streamflow, while other water from precipitation infiltrates the soil and
moves below the surface as groundwater discharge. Water vapor in the
atmosphere is commonly moved away from the source of evaporation by
wind and the movement of air masses. Consequently, most water falling as
precipitation comes from a source of evaporation that is located upwind.
Nonetheless, local sources of evaporation can contribute as much as 25-
33% of water in precipitation.
sgse Water Cycle
=
—
=<
votes storagein 7" ' Vater storage in the atmosp re
ors Me ‘5 Sublimation
f 1 _ Evapo ranspiration
Des
Evaporation
‘ 5
Department of the Interior : Groundwater storage es Illustration by John M. Evans
US 7
U.S. Geological Survey http://ga_water.usgs.gov/edu/watercycle htm!
The Water Cycle. Figure illustrates the water cycle on,
above, and below the Earth's surface. Source: U.S.
Department of the Interior and U.S. Geological Survey, The
Water Cycle.
Human Interactions with The Water Cycle
Freshwater supply is one of the most important provisioning ecosystem
services on which human well-being depends. By 2000, the rate of our
water extraction from rivers and aquifers had risen to almost 4000 cubic
kilometers per year. The greatest use of this water is for irrigation in
agriculture, but significant quantities of water are also extracted for public
and municipal use, as well as industrial applications and power generation.
Other major human interventions in the water cycle involve changes in land
cover and infrastructure development of river networks. As we have
deforested areas for wood supply and agricultural development we have
reduced the amount of vegetation, which naturally acts to trap precipitation
as it falls and slow the rate of infiltration into the ground. As a
consequence, surface runoff has increased. This, in turn, means flood peaks
are greater and erosion is increased. Erosion lowers soil quality and
deposits sediment in river channels, where it can block navigation and harm
aquatic plants and animals. Where agricultural land is also drained these
effects can be magnified. Urbanization also accelerates streamflow by
preventing precipitation from filtering into the soil and shunting it into
drainage systems. Additional physical infrastructure has been added to river
networks with the aim of altering the volume, timing, and direction of water
flows for human benefit. This is achieved with reservoirs, weirs, and
diversion channels. For example, so much water is removed or redirected
from the Colorado River in the western United States that, despite its
considerable size, in some years it is dry before reaching the sea in Mexico.
We also exploit waterways through their use for navigation, recreation,
hydroelectricity generation and waste disposal. These activities, especially
waste disposal, do not necessarily involve removal of water, but do have
impacts on water quality and water flow that have negative consequences
for the physical and biological properties of aquatic ecosystems.
The water cycle is key to the ecosystem service of climate regulation as
well as being an essential supporting service that impacts the function of all
ecosystems. Consider the widespread impacts on diverse natural and human
systems when major droughts or floods occur. Consequently, human
disruptions of the natural water cycle have many undesirable effects and
challenge sustainable development. There are two major concerns. First, the
need to balance rising human demand with the need to make our water use
sustainable by reversing ecosystem damage from excess removal and
pollution of water. Traditionally, considerable emphasis has been on finding
and accessing more supply, but the negative environmental impacts of this
approach are now appreciated, and improving the efficiency of water use is
now a major goal. Second, there is a need for a safe water supply in many
parts of the world, which depends on reducing water pollution and
improving water treatment facilities.
The Natural Nitrogen Cycle
The vast majority of nitrogen on Earth is held in rocks and plays a minor
role in the nitrogen cycle. The second largest pool of nitrogen is in the
atmosphere. Most atmospheric nitrogen is in the form of N> gas, and most
organisms are unable to access it. This is significant because nitrogen is an
essential component of all cells—for instance, in protein, RNA, and DNA
—and nitrogen availability frequently limits the productivity of crops and
natural vegetation. Atmospheric nitrogen is made available to plants in two
ways. Certain microbes are capable of biological nitrogen fixation,
whereby N> is converted into ammonium, a form of nitrogen that plants can
access. Many of these microbes have formed symbiotic relationships with
plants—they live within the plant tissue and use carbon supplied by the
plant as an energy source, and in return they share ammonia produced by
nitrogen fixation. Well-known examples of plants that do this are peas and
beans. Some microbes that live in the soil are also capable of nitrogen
fixation, but many are found in a zone very close to roots, where significant
carbon sources are released from the plant. Together these biological
nitrogen fixing processes on land, coupled with others that take place at sea,
generate an annual flux out of the atmosphere of approximately 200 MtN
(megatonnnes of nitrogen or 200,000,000 tonnes of nitrogen). Lightning
causes nitrogen and oxygen in the atmosphere to react and produce nitrous
oxides that fall or are washed out of the atmosphere by rain and into the
soil, but the is flux is much smaller (30 MtN per year at most) than
biological nitrogen fixation.
While the inputs of nitrogen from the atmosphere to the biosphere are
important, the majority (90%) of nitrogen used by plants for growth each
year comes from ammonification of organic material. Organic material is
matter that comes from once-living organisms. Ammonification (or
mineralization) is the release of anmonia by decomposers (bacteria and
fungi) when they break down the complex nitrogen compounds in organic
material. Plants are able to absorb (assimilate) this ammonia, as well as
nitrates, which are made available by bacterial nitrification. The cycle of
nitrogen incorporation in growing plant tissues and nitrogen release by
bacteria from decomposing plant tissues is the dominant feature of the
nitrogen cycle and occurs very efficiently. Nitrogen can be lost from the
system in three main ways. First, denitrifying bacteria convert nitrates to
nitrous oxide or N> gases that are released back to the atmosphere.
Denitrification occurs when the bacteria grow under oxygen-depleted
conditions, and is therefore favored by wet and waterlogged soils.
Denitrification rates almost match biological nitrogen fixation rates, with
wetlands making the greatest contribution. Second, nitrates are washed out
of soil in drainage water (leaching) and into rivers and the ocean. Third,
nitrogen is also cycled back into the atmosphere when organic material
burns.
Store
a EA Gaseous
ue 7 Mitogen le yA
QF, Nitrogen Z
Hae ntning Or
“!! Eixatio
Bacteria
Fixation
The Nitrogen Cycle. Figure illustrates the nitrogen cycle
on, above, and below the Earth's surface. Source: Physical
Geography Fundamentals eBook.
Human Interactions With The Nitrogen Cycle
Humans are primarily dependent on the nitrogen cycle as a supporting
ecosystem service for crop and forest productivity. Nitrogen fertilizers are
added to enhance the growth of many crops and plantations. The enhanced
use of fertilizers in agriculture was a key feature of the green revolution that
boosted global crop yields in the 1970s. The industrial production of
nitrogen-rich fertilizers has increased substantially over time and now
matches more than half of the input to the land from biological nitrogen
fixation (90 MtN each year). If the nitrogen fixation from leguminous crops
(e.g. beans, alfalfa) is included, then the anthropogenic flux of nitrogen
from the atmosphere to the land exceeds natural fluxes to the land. As
described above, most ecosystems naturally retain and recycle almost all of
their nitrogen. The relatively little nitrogen that is being gained or lost by
fluxes to the atmosphere and water cycle is also nearly being balanced.
When humans make large additions of nitrogen to ecosystems leakage often
results, with negative environmental consequences. When the amount of
nitrate in the soil exceeds plant uptake, the excess nitrate is either leached in
drainage water to streams, rivers, and the ocean or denitrified by bacteria
and lost to the atmosphere. One of the main gases produced by denitrifying
bacteria (nitrous oxide) is an important greenhouse gas that is contributing
to human-induced global warming. Other gases released to the atmosphere
by denitrifying bacteria, as well as ammonia released from livestock and
sewage sludge, are later deposited from the atmosphere onto ecosystems.
The additional nitrogen from this deposition, along with the nitrogen
leaching into waterways, causes eutrophication. Eutrophication occurs
when plant growth and then decay is accelerated by an unusually high
supply of nitrogen, and it has knock-on effects, including the following:
certain plant species out-competing other species, leading to biodiversity
loss and altered ecosystem function; algal blooms that block light and
therefore kill aquatic plants in rivers, lakes, and seas; exhaustion of oxygen
supplies in water caused by rapid microbial decomposition at the end of
algal blooms, which kills many aquatic organisms. Excess nitrates in water
supplies have also been linked to human health problems. Efforts to reduce
nitrogen pollution focus on increasing the efficiency of synthetic fertilizer
use, altering feeding of animals to reduce nitrogen content in their excreta,
and better processing of livestock waste and sewage sludge to reduce
ammonia release. At the same time, increasing demand for food production
from a growing global population with a greater appetite for meat is driving
greater total fertilizer use, so there is no guarantee that better practices will
lead to a reduction in the overall amount of nitrogen pollution.
Review Questions
Exercise:
Problem:
There is approximately 2,000 cubic kilometers of water stored in rivers
around the world. Using the terms water cycle, flux and pool, describe
under what conditions removing 1000 cubic kilometers per year from
rivers for human use could be sustainable.
Exercise:
Problem:
Each year, around a quarter of the carbon dioxide found in the
atmosphere is turned into plant matter via photosynthesis. Does this
mean that, in the absence of human activity, all carbon dioxide would
be removed from the atmosphere in around four years? Explain your
answer.
Exercise:
Problem:
The water, carbon, and nitrogen cycles are all influenced by human
activity. Can you describe a human activity that impacts all three
cycles? In your example, which of the cycles is most significantly
altered?
References
Le Quere, C., Raupach, M. R., Canadell, J. G., Marland, G., Bopp, L.,
Ciais, P., et al. (2009, December). Trends in the sources and sinks of carbon
dioxide. Nature Geoscience, 2, 831-836. doi: 10.1038/ngeo689
Millennium Ecosystem Assessment (2005). Ecosystems and Human Well-
Being: Synthesis. Washington DC. Retrieved from
Glossary
ammonification
The release of ammonia by decomposerswhen they break down the
complex nitrogen compounds in organic material
anthropogenic CO, emissions
Human release of CO, into the atmosphere by burning fossil fuels and
changing land use.
assimilation
Acquisition and incorporation of nutrients or resources by plants e.g.
nitrogen or carbon.
biogeochemical cycles
A concept describing how chemical elements (e.g., nitrogen, carbon)
or molecules (e.g. water) are transformed and stored by both physical
and biological components of the Earth system.
biological components of the earth system
All living organisms, including plants, animals and microbes.
biological nitrogen fixation
Where microbes convert N> gas in the atmosphere into ammonium that
can be absorbed by plants.
decomposers
Bacteria and fungi that break down rotting organic material, releasing
component elements in the process.
denitrifying bacteria
Microbes that convert nitrates to nitrous oxide or N> gases that are
released back to the atmosphere.
eutrophication
Accelerated plant growth and decay caused by nitrogen pollution.
evaporation
The process whereby water is converted from a liquid into a vapor, as
a result of absorbing energy (usually from solar radiation).
evapotranspiration
Evaporation from vegetated land that includes water transpired by
plants as well as evaporation from open water and soils.
fluxes
Transformations or flow of materials from one pool to another in a
biogeochemical cycle.
greenhouse gases
Gases in Earth's atmosphere that absorb long-wave radiation and retain
heat.
groundwater discharge
Flow of water from below-ground into rivers, lakes, or the ocean.
infiltration
Flow of water from the land surface into soils and rocks.
land use change
Human change in the use of land, e.g. deforestation or urbanization.
leaching
Loss of nitrates from soil in drainage water
nitrification
Conversion of ammonia into nitrates by microbes.
photosynthesis
The process in which plants use energy from sunlight to combine CO»
from the atmosphere with water to make sugars, and in turn build
biomass.
physical components of the earth system
Nonliving factors such as rocks, minerals, water, climate, air, and
energy.
pools
Amounts of material in biogeochemical cycles that share some
common characteristic and are relatively uniform in nature.
precipitation
The conversion of atmospheric water from vapor into liquid (rain) or
solid forms (snow, hail) that then fall to Earth's surface.
primary producers
The primary entry point of carbon into the biosphere—in nearly all
land and aquatic ecosystems plants perform this role by virtue of
photosynthesis.
respiration
Metabolic process in all organisms that generates energy and
synthesizes biomass while releasing CO, as a by-product.
streamflow
Flow of water in streams.
surface runoff
Flow of water over the land surface.
Biodiversity, Species Loss, and Ecosystem Function
In this module, the following topics are covered: 1) biodiversity, 2) trends
in biodiversity loss with reference to species and ecosystems, 3) ways
human activity affects biodiversity, and 4) biodiversity loss effects on
people
Learning Objectives
After reading this module, students should be able to
¢ define biodiversity
e articulate current trends in biodiversity loss with reference to species
and ecosystems
e explain some of the ways human activity affects biodiversity
e explain how biodiversity loss concerns people
What is Biodiversity?
You're probably familiar with the word, biodiversity, whether or not you
can give an exact definition of it. It's common on the signs at zoos, parks,
and nature centers, and it's often used without explanation or definition.
Most people understand biodiversity in general terms as the number and
mix of plant and animal species that occurs in a given place. Scientists are
more precise and include more in their definition. The International Union
for the Conservation of Nature (IUCN), which coordinates efforts to
catalogue and preserve biodiversity worldwide, defines biodiversity as "the
variability among living organisms from all sources including terrestrial,
marine and other aquatic ecosystems, and the ecological complexes of
which they are part; this includes diversity within species, between species,
and of ecosystems." Rather than just species, biodiversity therefore includes
variation from the level of genes and genomes to that of ecosystems to
biomes.
Even within a single ecosystem, the numbers of species can be impressive.
For example, there is a large region of dry forest and savanna in Brazil
known as the Cerrado (see Figure Cerrado Forest). This ecosystem alone
hosts over 10,000 species of plants, almost 200 species of mammals, over
600 species of birds, and about 800 species of fish.
Cerrado Forest. Photograph of the Cerrado Forest. Source:
C2rik via Wikimedia Commons,
Generally, biodiversity is greatest in tropical areas—especially
"rainforests'"—but there are terrestrial biodiversity "hotspots" on all the
major continents. (View an interactive map of hotspots.)
Current Trends: Species Loss and Decline
One way scientists gauge trends in biodiversity is by monitoring the fate of
individual species of animals and plants. For more than 40 years, the IUCN
has compiled information in the "Red List of Threatened Species," which
"provides a snapshot of what is happening to species around the world."
Updates to the Red List are released every four years. Here is how the
authors of the most recent one, released in 2008, characterize the news it
holds: "The overwhelming message" from the 2008 Red List, they write, "is
that the world is losing species and that the rate of loss appears to be
accelerating in many taxonomic groups" (Vie, Hilton-Taylor, & Stuart,
2008, p. 38).
Estimated Number Number of Number Number
Number of species threatened threatened,as threatened, as
of described evaluated species’ % ofspecies % of species
described*® evaluated™
—
~
ee aaa
| 21% | 21%
| 12% | 12%
| 5% | 81%
| 30% | 80%
| 4% | 87%
10% | 22%
Ee ee
| 1% 4H
a a
p11% | 27%
| O% SH
| 5% BH
a a a;
a a ee
| 0.20% | 41%
a ae
| 1% | 8%
| 1% | HC
a a
a a a 7
ee
a a a;
| O% 1H
38% | 70%
eee ee
| O% | 100%
| O% | 100%
a a ee;
1% | 88%
38%
Summary of Threatened Species. Table lists the numbers and
proportions of species assessed as threatened on the 2008 IUCN Red
List by major taxonomic group. Source: IUCN Red List, Wildlife in a
Changing_World 2008, p. 17. Please see IUCN Terms of Use for
copyright restrictions.
Vertebrates
Scientists know much more about the state of vertebrates—especially
mammals, birds, and amphibians—than they do about other forms of
animal life. Every one of the 5,488 species of mammals that have been
described, for example, has been evaluated for purposes of the Red List. Of
them, 76 species have become extinct since 1500, and two, Pere David's
deer, which is native to China, and the scimitar oryx from Africa survive
only in managed facilities. Another 29 of the mammal species listed as
critically endangered are also tagged as "possibly extinct;" they are very
likely gone, but the sort of exhaustive surveys required to confirm that fact
have not been conducted. Overall, approximately 22% of mammal species
worldwide are known to be threatened or extinct. (In the terms of the Red
List, the broad designation "threatened" includes three levels of risk for
extinction in the wild: Vulnerable [high], Endangered [higher], and
Critically Endangered [highest].)
The Red List categorizes a smaller proportion of the world's 9,990
described bird species—14%—as threatened or extinct. But the raw number
of species lost since 1500 is at least 134, and four more species persist only
in zoos. Another 15 species of birds are considered possibly extinct. The
fact that 86% of bird species are categorized as "not threatened" is good
news in the context of the Red List.
Passenger Pigeons. North American passenger pigeons lived
in enormous flocks and were once the most numerous birds on
earth. Market hunting on a massive scale and habitat
destruction combined to extinguish them as a species in the
early twentieth century. Source: Ltshears via Wikimedia
Commons
Among the well-studied vertebrates, amphibians are faring especially
poorly. Of the more than 6,000 known species of amphibians, 38 have
become extinct worldwide since 1500, and another one, the Wyoming toad,
survives only in captivity. Another 120 species are considered possibly
extinct. Overall, 2,030, or one-third of the world's amphibian species are
known to be threatened or extinct. More troubling still, many amphibian
species—42.5%—are reported to be declining, and that number is probably
low, since trend information is unavailable for 30.4% of species.
Monteverde Golden Toad. The golden toad of Monteverde,
Costa Rica, is one of 11 species of amphibians to become extinct
since 1980. Habitat loss and chytrid fungus. Source: U.S. Fish and
Wildlife Service via Wikimedia Commons.
Only small proportions of the world's species of reptiles and fish have been
evaluated for purposes of the Red List. Among those, the numbers of
species that fall into the threatened category are very high: 1,275 of the
3,481 evaluated species, or 37%, for fish; and 423 of 1,385 evaluated
species, or 31%, for reptiles. It should be noted, however, that these
percentages are likely overestimates, since species of concern are more
likely to be selected for evaluation than others.
Invertebrates
The category "invertebrates" lumps together the vast majority of multi-
cellular animals, an estimated 97% of all species. It includes everything
from insects and arachnids, to mollusks, crustaceans, corals, and more. Few
of these groups have been assessed in a comprehensive way, and so as with
fish and reptiles, the Red List percentages of threatened species are skewed
high. But assessments within some groups call attention to disturbing, large-
scale trends. For example, 27% of the world's reef-building corals are
already considered threatened, and many more of them are experiencing
rates of decline that move them toward threatened status. The demise of
reef-building corals has magnified ecological impacts, since so much other
marine life depends on them.
Pink Soft Coral with Reef
Fish. Photograph shows some
pink, soft coral with reef fish
nearby. Source: Linda Wade
via National Oceanic &
Atmospheric Administration
(NOAA).
It should be understood that information about familiar creatures such as
amphibians, mammals, and birds is just a beginning, and that even with the
inclusion of some invertebrates the Red List does not provide a
comprehensive picture of life on Earth. Scientists have described fewer than
2 million of the 8-9 million species of organisms thought to exist, most of
which are insects. And of those 2 million, the status of only 44,838 has been
assessed by IUCN.
In addition, it should be understood that among the species that have been
assessed so far, there is a strong bias toward terrestrial vertebrates and
plants, especially the ones that occur where biologists have visited
frequently. Red List assessments also tend to focus on species that are likely
to be threatened, since the effort also has the aim of enabling people to
conserve species.
Whereas extinction is the global loss of a species, the elimination of species
at a local level-known as extirpation — also poses threats to the integrity
and sustainability of ecosystems. Widespread extirpation obviously leads to
threatened or endangered status, but absence of species, even at a local
scale, can affect ecosystem function. For example, by the mid-1920s
wolves had been extirpated from Yellowstone National Park, although they
continued to thrive elsewhere. When wolves were reintroduced to the park
in the mid-1990s, numbers of elk (a main prey item) decreased
significantly. This, in turn, reduced browsing pressure and had a significant
effect on the vegetation and plant communities. What mattered for
ecosystem function in Yellowstone was whether wolves were present there,
not just whether the species survived somewhere.
The human activities that account for extinction and extirpation vary
considerably from one species to another, but they fall into a few broad
categories: habitat destruction and fragmentation; intentional and
unintentional movement of species that become invasive (including disease-
causing organisms); over-exploitation (unsustainable hunting, logging,
etc.); habitat/ecosystem degradation (e.g. pollution, climate change).
Current Trends: Ecosystem Loss and Alteration
Another way of gauging biodiversity involves assessment on the scale of
ecosystems. The causes of wholesale losses of ecosystems are much the
same as those driving extinction or endangerment of species, with habitat
loss and fragmentation being the primary agent. Worldwide, for example,
the conversion of land to agriculture and cultivation have led to significant
losses in grassland ecosystems. In North America, nearly 70% of the
tallgrass prairie ecosystem (which once covered 142 million acres) has been
converted to agriculture, and losses from other causes, such as urban
development, have brought the total to about 90%. Current estimates
indicate that agricultural activity and cultivation systems now cover nearly
25% of the Earth's surface.
Tropical rainforests, which are the habitats for nearly half of the world's
plant and animal species, covered about 4 billion acres in past centuries, but
only 2.5 billion acres remain and nearly 1% is being lost annually. Losses
have been especially severe in the "paleo" or old world tropics that include
Africa and Southeast Asia.
The category "wetlands" includes many types of ecosystems, but current
estimates indicate that about 50% of the world's wetland habitat has been
lost. The former extent of wetland habitats worldwide (fresh, brackish and
salt) is difficult to determine but certainly exceeded a billion acres.
Species and Ecosystem Loss in Perspective
To understand why biologists talk about ongoing losses of species and
ecosystems as the "biodiversity crisis," it is useful to put current and
projected rates of species loss into historical perspective. Over the history
of life on Earth—a span of 3.5 billion years—nearly all species that existed
eventually became extinct. This, of course, is coupled with the processes of
speciation and biological diversification. Rates of extinction and
diversification have fluctuated significantly over geologic time. For
extinction, paleontologists have detected five episodes of mass extinction
over the last 540 million years. These periods contrast with the relatively
constant "background rate" of extinction observed over the geologic record,
and include the relatively well-known event 65 million years ago when
most of the extant dinosaurs went extinct. By definition, these episodes are
characterized by the comparatively rapid loss of at least three-fourths of the
species thought to exist at the onset of the event.
Recently, the question has been posed whether present-day rates of species
loss constitute a sixth episode of mass extinction (Barnosky, et al., 2011).
Even with caveats about uncertainty in how many species there are today
(only a fraction of the estimated total have been described, especially for
plants, invertebrates, and microbes) and about comparisons of the fossil
record with modern data, it appears that estimated rates of loss in the near
future could rival those of past mass extinctions. Some estimates indicate
that we will see a 30% loss of species within decades. Put another way,
forecasted rates of species loss could be as much as 1000 to 10,000 times
higher than background rates.
How Does Loss of Biodiversity Concern People?
As we learn more about biodiversity, it is becoming clear that there is often
a positive association between biodiversity and the integrity of biological
systems. This is not to say more diverse systems are "better;" rather, this
means that systems with a relatively pristine complement of biological and
abiotic or physical components tend to be more resilient and robust.
Whereas this is rather nebulous, there is little doubt that the integrity of
ecosystems is of fundamental importance to nearly all phases of human life
and culture.
Often called ecological services, the products and processes associated with
biological systems are of immense value to the well being of people. An
incomplete list of these services and products includes the formation of soil
and cycling of nutrients; provisioning of food, fresh water, fuel, fiber, and
recreation opportunities; the regulation of climate, flooding, and disease.
The value of these services is often overlooked or simply taken for granted,
but one global estimate puts it somewhere between $16-64 trillion annually.
From global food security, to a source of medicines, to even the oxygen in
Our air, we are dependent on biodiversity and the sustained integrity of
ecological systems. Nature is also the basis for a significant part of aesthetic
and spiritual values held by many cultures.
Given this dependence, it is astounding that many are unaware or—even
worse—apathetic about what is occurring and what will likely happen in the
near future to our biological resources. We do not contend that any loss of
species will affect productivity or function at the ecosystem level. The
function of one species can be redundant with others and its loss may not
lead to a significant change at the ecosystem level. Whereas redundancy
can contribute to the resiliency of natural systems, that should not be a
source of comfort. Much ecological theory posits thresholds of species loss
beyond which the integrity of ecosystems is threatened; unexpected and
possibly permanent new "states" may result. Once a community or
ecosystem reaches an alternative state, there may be little that can be done
to restore or remediate the system. Therefore, even under optimistic
scenarios for rates of species loss (from the local to global scale) we are
facing an uncertain environment.
Review Questions
Exercise:
Problem: What is the difference between extinction and extirpation?
Exercise:
Problem:
What are some human activities that impact species diversity and
ecosystem function?
Exercise:
Problem:
Does the loss of one species lead to loss of ecosystem function? Why
or why not?
Exercise:
Problem: How does biodiversity promote sustainability?
References
Barnosky, A.D., Matzke, N., Tomiya, S., Wogan, G.O.U., Swartz, B.,
Quental, T.B., et al. (2011, March). Has the Earth's sixth mass extinction
already arrived? Nature, 471, 51-57. doi:10.1038/nature09678
Vie, J-C, Hilton-Taylor, C. & Stuart S.N. (Eds.). (2009). Wildlife in a
Changing World: An Analysis of the 2008 IUCN Red List of Threatened
Species™, Gland, Switzerland: IUCN. Retrieved from
Glossary
biodiversity
The number of different species within an ecosystem (or globally).
Biodiversity is also considered a metric of ecosystem health.
ecosystem function
Processes such as decomposition, production, nutrient cycling, and
fluxes of nutrients and energy that allow an ecosystem to maintain its
integrity as a habitat.
extinction
The death of all individuals within a species. A species may be
functionally extinct when a low number of surviving individuals are
unable to reproduce.
extirpation
Local extinction of a species; elimination or removal of a species from
the area of observation.
ecological services
Ecosystem functions that are essential to sustaining human health and
well-being. Examples include provisioning services such as food, fiber
and water; regulating services such as climate, flood, and disease
control; cultural services such as spiritual and recreational benefits,
and supporting services such as nutrient cycling. Also called
ecosystem services.
Soil and Sustainability
In this module, the following topics are covered: 1) soil's importance to
society, 2) the formation of soil profiles, 3) soil constituents for plant
growth and nutrient uptake, and 4) soil's relationship with agricultural
sustainability and ecological processes
Learning Objectives
After reading this module, students should be able to
¢ define soil and comment on its importance to society
¢ describe how soil profiles form
e explain the importance of soil constituents for plant growth and
nutrient uptake
¢ understand the importance of soil to agricultural sustainability and
ecological processes
Soil Profiles and Processes
What Is Soil?
The word "soil" has been defined differently by different scientific
disciplines. In agriculture and horticulture, soil generally refers to the
medium for plant growth, typically material within the upper meter or two
(see Figure Soil Profile).
Soil Profile. Photograph shows a soil
profile from South Dakota with A, E, and
Bt horizons. The yellow arrows
symbolize translocation of fine clays to
the Bt horizon. The scale is in feet.
Source: University of Idaho and modified
by D. Grimley.
We will use this definition in this chapter. In common usage, the term soil is
sometimes restricted to only the dark topsoil in which we plant our seeds or
vegetables. In a more broad definition, civil engineers use the term soil for
any unconsolidated (soft when wet) material that is not considered bedrock.
Under this definition, soil can be as much as several hundred feet thick!
Ancient soils, sometimes buried and preserved in the subsurface, are
referred to as paleosols (see Figure Modern versus Buried Soil Profiles)
and reflect past climatic and environmental conditions.
Modern versus Buried Soil Profiles.
A buried soil profile, or paleosol
(above geologist 's head), represents
soil development during the last
interglacial period. A modern soil
profile (Alfisol) occurs near the land
surface. Source: D. Grimley.
From a somewhat philosophical standpoint, soil can be viewed as the
interface between the atmosphere and the earth's crust, and is sometimes
referred to as the skin of the earth. Soil also incorporates aspects of the
biosphere and the hydrosphere. From a physical standpoint, soil contains
solid, liquid, and gaseous phases. The solid portion of the soil consists
predominantly of mineral matter, but also contains organic matter (humus)
and living organisms. The pore spaces between mineral grains are filled
with varying proportions of water and air.
Importance of Soil
Soil is important to our society as it provides the foundation for most of the
critical aspects of civilization. Our building structures and homes, food,
agricultural products, and wood products all rely on soil. Forests, prairies,
and wetlands all have a dependence on soil. Of course, soil is also a critical
component for terrestrial life on earth, including most animals, plants, and
many microorganisms.
Soil plays a role in nearly all natural cycles on the earth's surface. Global
cycling of key nutrients, such as Carbon (C), Nitrogen (N), Sulfur (S), and
Phosphorous (P), all pass through soil. In the hydrologic cycle, soil helps to
mediate the flow of precipitation from the land surface into the groundwater
or can control stormwater runoff into lakes, streams, bays, and oceans. Soil
microorganisms or microflora can help to modify or destroy environmental
pollutants.
Soil Forming Factors
The fundamental factors that affect soil genesis can be categorized into five
elements: climate, organisms, relief, parent material, and time. One could
say that the landscape relief, climate, and organisms dictate the local soil
environment, and act together to cause weathering and mixing of the soil
parent material over time. The soil forming factors are interrelated and
interdependent, but considered independently they provide a useful
framework for discussion and categorization.
As soil is formed it often has distinct layers, which are formally described
as "horizons." Upper horizons (labeled as the A and O horizons) are richer
in organic material and so are important in plant growth, while deeper
layers (such as the B and C horizons) retain more of the original features of
the bedrock below.
Climate
The role of climate in soil development includes aspects of temperature and
precipitation.Soils in very cold areas with permafrost conditions (Gelisols)
tend to be shallow and weakly developed due to the short growing season.
Organic rich surface horizons are common in low-lying areas due to limited
chemical decomposition. In warm, tropical soils (Ultisols, Oxisols), other
factors being equal, soils tend to be thicker, with extensive leaching and
mineral alteration. In such climates, organic matter decomposition and
chemical weathering occur at an accelerated rate.
Organisms
Animals, plants, and microorganisms all have important roles in soil
development processes, in providing a supply of organic matter, and/or in
nutrient cycling. Worms, nematodes, termites, ants, gophers, moles,
crayfish, etc. all cause considerable mixing of soil and help to blend soil,
aerate and lighten the soil by creating porosity, and create characteristic
natural soil structure over time. Animal life, such as insects and mammals,
can cause irregularities in the soil horizons.
Plant life provides much organic matter to soil and helps to recycle nutrients
with uptake by roots in the subsurface. The type of plant life that occurs in a
given area, such as types of trees or grasses, depends on the climate, along
with parent material and soil type. So there are clearly feedbacks among the
soil forming factors. With the annual dropping of leaves and needles, trees
tend to add organic matter to soil surfaces, helping to create a thin, organic-
rich A or O horizon over time. Grasses, on the other hand, have a
considerable root mass, in addition to surficial organic material, that is
released into the soil each fall for annuals and short-lived perennials. For
this reason, grassland soils (Mollisols) have much thicker A horizons with
higher organic matter contents, and are more agriculturally productive than
forest soils. Grasses release organic matter to soils that is more rich in base
cations, whereas leaf and needle litter result in release of acids into the soil.
Microorganisms aid in the oxidation of organic residues and in production
of humus material. They also play a role in iron oxidation-reduction cycles,
fine-grained mineral dissolution (providing nutrients to soil solutions), and
mineral neoformation. New research is continually expanding our
knowledge of the role of microorganisms in plant growth, nutrient cycling,
and mineral transformations.
Relief (Topography and Drainage)
The local landscape can have a surprisingly strong effect on the soils that
form on site. The local topography can have important microclimatic effects
as well as affecting rates of soil erosion. In comparison to flat regions, areas
with steep slopes overall have more soil erosion, more runoff of rainwater,
and less water infiltration, all of which lead to more limited soil
development in very hilly or mountainous areas. In the northern
hemisphere, south-facing slopes are exposed to more direct sunlight angles
and are thus warmer and drier than north-facing slopes. The cooler, moister
north-facing slopes have a more dynamic plant community due to less
evapotranspiration and, consequently, experience less erosion because of
plant rooting of soil and have thicker soil development.
Soil drainage affects iron oxidation-reduction states, organic matter
accumulation and preservation, and local vegetation types. Well-drained
soils, generally on hills or sideslopes, are more brownish or reddish due to
conversion of ferrous iron (Fe**) to minerals with ferric (Fe**) iron. More
poorly drained soils, in lowland, alluvial plains or upland depressions, tend
more be more greyish, greenish-grey (gleyed), or dark colored, due to iron
reduction (to Fe**) and accumulation and preservation of organic matter in
areas tending towards anoxic. Areas with poor drainage also tend to be
lowlands into which soil material may wash and accumulate from
surrounding uplands, often resulting in overthickened A or O horizons. In
contrast, steeply sloping areas in highlands may experience erosion and
have thinner surface horizons.
Parent Material
The parent material of a soil is the material from which the soil has
developed, whether it be river sands, lake clays, windblown loess, shoreline
deposits, glacial deposits, or various types of bedrock. In youthful soils, the
parent material has a clear connection to the soil type and has significant
influence. Over time, as weathering processes deepen, mix, and alter the
soil, the parent material becomes less recognizable as chemical, physical,
and biological processes take their effect. The type of parent material may
also affect the rapidity of soil development. Parent materials that are highly
weatherable (such as volcanic ash) will transform more quickly into highly
developed soils, whereas parent materials that are quartz-rich, for example,
will take longer to develop. Parent materials also provide nutrients to plants
and can affect soil internal drainage (e.g. clay is more impermeable than
sand and impedes drainage).
Time
In general, soil profiles tend to become thicker (deeper), more developed,
and more altered over time. However, the rate of change is greater for soils
in youthful stages of development. The degree of soil alteration and
deepening slows with time and at some point, after tens or hundreds of
thousands of years, may approach an equilibrium condition where erosion
and deepening (removals and additions) become balanced. Young soils (<
10,000 years old) are strongly influenced by parent material and typically
develop horizons and character rapidly. Moderate age soils (roughly 10,000
to 500,000 years old) are slowing in profile development and deepening,
and may begin to approach equilibrium conditions. Old soils (>500,000
years old) have generally reached their limit as far as soil horizonation and
physical structure, but may continue to alter chemically or mineralogically.
To be sure, soil development is not always continual. Geologic events can
rapidly bury soils (landslides, glacier advance, lake transgression), can
cause removal or truncation of soils (rivers, shorelines) or can cause soil
renewal with additions of slowly deposited sediment that add to the soil
(wind or floodplain deposits). Biological mixing can sometimes cause soil
regression, a reversal or bump in the road for the normal path of increasing
development over time.
Ecological and Societal Aspects of Soil
As the medium for native plant growth, agriculture, building construction,
waste disposal, and a pathway for groundwater infiltration, soil plays an
important role for many key activities of our society. Soil scientists,
agronomists, foresters, plant biologists, land-use planners, engineers,
archeologists, and geologists, among others, all consider soil type
(composition, texture, structure, density, etc.) in many aspects of their
research or work. Below are some examples of the importance of soils in
natural plant growth, in agriculture, and related societal issues. The long-
term sustainability of soil is vital to both human ecology, even in modern
society, and the ecology of our natural surroundings.
Soil-Plant Relations: Natural Processes
Soil plays a key role in plant growth. Beneficial aspects to plants include
providing physical support, heat, water, nutrients, and oxygen. Heat, light,
and oxygen are also obtained by the atmosphere, but the roots of many
plants also require oxygen. Elemental nutrients, dissolved in soil water
solution, are derived from soil minerals and organic material (see Figure
Soil-Plant Nutrient Cycle).
respiration
cecomposion
nutrient
losses
Soil-Plant Nutrient Cycle. Figure illustrates
the uptake of nutrients by plants in the
forest" soil ecosystem. Source: U.S.
Geological Survey.
Plants mainly obtain nutrients from dissolved soil solutions. Though many
aspects of soil are beneficial to plants, excessively high levels of trace
metals (either naturally occurring or anthropogenically added) or applied
herbicides can be toxic to some plants.
The ratio of solids/water/air in soil is also critically important to plants for
proper oxygenation levels and water availability. Too much porosity with
air space, such as in sandy or gravelly soils, can lead to less available water
to plants, especially during dry seasons when the water table is low. Too
much water, in poorly drained regions, can lead to anoxic conditions in the
soil, which may be toxic to some plants. Hydrophytic vegetation can handle
anoxic conditions and is thus suitable to poorly drained soils in wetland
areas.
Nutrient Uptake by Plants
Several elements obtained from soil are considered essential for plant
growth. Macronutrients, including C, H, O, N, P, K, Ca, Mg, and S, are
needed by plants in significant quantities. C, H, and O are mainly obtained
from the atmosphere or from rainwater. These three elements are the main
components of most organic compounds, such as proteins, lipids,
carbohydrates, and nucleic acids. Oxygen generally serves as an electron
acceptor and is required by roots of many plants. The other six elements (N,
P, K, Ca, Mg, and S) are obtained by plant roots from the soil and are
variously used for protein synthesis, chlorophyll synthesis, energy transfer,
cell division, enzyme reactions, and osmotic or ionic regulation.
Micronutrients are essential elements that are needed only in small
quantities, but can still be limiting to plant growth since these nutrients are
not so abundant in nature. Micronutrients include iron (Fe), manganese
(Mn), boron (B), molybdenum (Mo), chlorine (Cl), zinc (Zn), and copper
(Cu). There are some other elements that tend to aid plant growth but are
not absolutely essential.
Micronutrients and macronutrients are desirable in particular concentrations
and can be detrimental to plant growth when concentrations in soil solution
are either too low (limiting) or too high (toxicity). Elemental nutrients are
useful to plants only if they are in an extractable form in soil solutions, such
as an exchangeable cation, rather than in a solid mineral grain. As nutrients
are used up in the microenvironment surrounding a plant's roots, the
replenishment of nutrients in soil solution is dependent on three aspects: (a)
the rate of dissolution/alteration of soil minerals into elemental constituents,
(b) the release rate of organically bound nutrients, and (c) the rate of
diffusion of nutrients through the soil solution to the area of root uptake.
Many nutrients move through the soil and into the root system as a result of
concentration gradients, moving by diffusion from high to low
concentrations. However, some nutrients are selectively absorbed by the
root membranes, such that elemental concentrations of solutions within
plants may differ from that in soil solutions. Most nutrients exist as
exchangeable cations that are acquired by roots from the soil solution—
rather than from mineral or particle surfaces. Inorganic chemical processes
and organic processes, such as the action of soil microorganisms, can help
to release elemental nutrients from mineral grains into the soil environment.
Soil Health and Agricultural Impacts: Soil as a Sustainable Resource
Soil Health and Sustainability
Overall soil health can generally be defined as the capacity of the soil to
function in a way that infiltrates water and cycles nutrients to support plant
growth. Long term health of native soil is in many cases improved by
disturbing the soil less, growing a greater diversity of crops, maintaining
living roots in the soil, and keeping the soil covered with residue. Stable
soil aggregates are important for soil health as they promote proper
infiltration and thus limit the amount of water runoff —this has the added
benefit of reducing soil erosion and downstream flooding and
sedimentation.
Management of soil on farms may include use of tillage, fertilizer,
pesticides, and other tools that may improve soil health if used correctly;
however, significant damage to soil may result otherwise. Tillage with a
plow or disk is can be physically disruptive to soil fauna and microbes. The
complex relations between soil and plant life, which have evolved into a
sustainable relationship in the natural world, can be disturbed chemically by
misuse or overuse of fertilizers or pesticides. Thus, to maintain soil health,
one needs to understand the chemical, biological, and physical processes
that operate in the natural soil profile. To the extent possible, we must work
with the complexity of processes that function in a healthy soil and limit our
disturbances to only those that are clear, practical necessity. Biodiversity is
another important aspect to consider, because increasing the biodiversity of
plants that are grown in soil can limit disease and pest problems and allow
for a better functioning food web. More diversity in plants above ground
leads to more diversity in the subsurface food web. Consequently,
increasing the diversity of appropriate crop rotation in agricultural lands can
ultimately lead to better soil health and limit problems in the long run.
Agriculture and Food Capacity
Soils on arable lands globally are a resource to society with potential use for
food production. Production is ultimately limited by soil type, climate,
hydrology, and land management. The native soil type is what has been
provided by the land, from centuries or millennia of soil development,
typically under mostly natural conditions under native plant vegetation. The
effect of human populations may have been to drain land for cultivation
(affecting hydrology), to modify the landscape, build structures, and to
remove native vegetation. Some modifications have aided with food
production. Others have had unintended consequences of causing land
degradation, such as salinization, topsoil erosion, compaction, pollution,
desertification, or depletion of soil nutrients.
Some of these issues are of serious concern in developing countries where
oversight and regulations protecting the land may not be in place. For
instance, overgrazing and rapid deforestation of the land, and generally poor
land management, can lower the organic matter content of surface soils,
thus lowering fertility and increasing the likelihood of topsoil erosion due to
removal of the protective vegetative covering. As the world's population
continues to increase, we will need to find ways to continually increase (or
more effectively utilize) food production capacity from an essentially fixed
amount of arable land worldwide. As population density has increased, crop
yields and the numbers of acres in production have been continually
increasing, with technological advances and more land in agriculture. This
is not a sustainable trend, though, since the land area on earth is finite. In
fact, some prime farmland is even being removed from production in
developed countries as urbanization and land development occur on the
ever-expanding edges of population centers. Efforts will need to be made to
preserve enough high yield farmland to be sustainable for future
generations.
Soil Compaction, Tillage, and Sustainable Practices
In modern agricultural practices, heavy machinery is used to prepare the
seedbed, for planting, to control weeds, and to harvest the crop. The use of
heavy equipment has many advantages in saving time and labor, but can
cause compaction of soil and disruption of the natural soil biota. Much
compaction is reversible and some is unavoidable with modern practices;
however, serious compaction issues can occur with excessive passage of
equipment during times when the soil has a high water content. The
problem with soil compaction is that increased soil density limits root
penetration depth and may inhibit proper plant growth.
Current practices generally encourage minimal tillage or no tillage in order
to reduce the number of trips across the field. With proper planning, this can
simultaneously limit compaction, protect soil biota, reduce costs (if
performed correctly), promote water infiltration, and help to prevent topsoil
erosion (see below). Tillage of fields does help to break up clods that were
previously compacted, so best practices may vary at sites with different soil
textures and composition. Crop rotation can also help to reduce bulk density
with planting of crops with different root depth penetration. Another aspect
of soil tillage is that it may lead to more rapid decomposition of organic
matter due to greater soil aeration. Over large areas of farmland, this has the
unintended consequence of releasing more carbon and nitrous oxides
(greenhouse gases) into the atmosphere, thereby contributing to global
warming effects. In no-till farming, carbon can actually become sequestered
into the soil. Thus, no-till farming may be advantageous to sustainability
issues on the local scale and the global scale.
Soil Erosion
Accelerated erosion of topsoil due to human activities and poor agricultural
land management is a potentially serious issue. The areas most vulnerable
to soil erosion include locations with thin organic (A and O) horizons and
hilly terrains (see Figure Water Erosion Vulnerability).
Water Erosion Vulnerability. Figure shows a global map of
soil erosion vulnerability and includes a photograph of water
and wind erosion. Source: U.S. Department of Agriculture,
National Resource Conservation Service, Rodney Burton via
Wikimedia Commons, and Jim Bain via Wikimedia Commons.
Some amount of soil erosion is a natural process along sloping areas and/or
in areas with soft or noncohesive materials susceptible to movement by
water, wind, or gravity. For instance, soil material can be mobilized in
strong windstorms, along the banks of rivers, in landslides, or by wave
action along coastlines. Yet most topsoil erosion results from water
influenced processes such as in rivers, creeks, ravines, small gullies, and
overland flow or sheetwash from stormwater runoff. Although some soil
erosion is natural, anthropogenic (human-induced) processes have greatly
accelerated the erosion rate in many areas. Construction and agriculture are
two of the more significant activities in our modern society that have
increased erosion rates. In both cases, the erosion of topsoil can be
significant if poor land management practices are used or if the area is
geologically sensitive. For instance, in the 1930's, drought conditions and
poor land management methods (lack of cover crops and rotation)
combined to result in severe wind erosion and dust storms in the Great
Plains of the United States, which came to be known as the Dust Bowl.
Deep plowing of soil and displacement of the original prairie grasses (that
once held the soil together) also contributed to the crisis. Once the natural
topsoil is eroded by wind or water, it is only slowly renewable to its former
pre-eroded condition. It may take anywhere from several decades to
hundreds of years to millennia, under replanted native vegetation, to restore
the soil to a relatively natural (pre-disturbed) state with its original physical,
chemical, and biological characteristics. Furthermore, when soil is eroded,
the particles become sedimented downstream in streams, rivers, lakes, and
reservoirs. If rapid, this sedimentation can deteriorate the water quality with
sediment and agricultural chemicals. Better land management practices,
such as more limited tillage or no-till practices, can help to greatly limit soil
erosion to a rate that is sustainable over the long term. Practices today are
somewhat improved overall, but more improvement in agricultural practices
are needed over large areas of farmland in the United States and other
countries to bring us on a path to long-term sustainability of agricultural
lands.
Deforestation due to logging, construction, or increased fire occurrences
can also cause significant increases in soil erosion in many areas globally
and may be a particular problem in developing countries. Removal of the
natural cover of vegetation enhances erosion since plant foliage tends to
buffer the intensity of rainfall and roots hold soil together and prevent
breakup and erosion. Furthermore, decomposing plant material provides a
protective cover of organic material on the soil surface. Watersheds with
large areas of construction or deforestation can experience several times the
natural erosion rate. In such watersheds, streams can become clogged with
unwanted sediment that disturbs the natural ecosystem and infills valuable
wetland areas, in addition to the problem of valuable topsoil loss from
upland areas.
Fertilizer Runoff, Ecological Effects, and Dead Zones
Nutrients in soil and water are generally beneficial when they exist at
naturally occurring levels. Nitrogen fertilizers have been applied to farm
fields for decades in order to maximize production of agricultural lands.
However, an unintended consequence is that the same nutrients can be
detrimental to aquatic ecosystems when introduced excessively for
agricultural or other purposes. Nitrogen (N) and Phosphorus (P) are
introduced by fertilizers that are used intensively in agriculture, as well as
golf courses and some lawns and gardens. Farm animal waste and sewage
also provide large amounts of reactive N and P. Phosphorus was formerly
used heavily as an additive in laundry and dishwater detergents, but since
the 1970's it has been phased out in both through a combination of state and
federal regulations. Overall, our modern society has altered the global N
and P cycles such that there is an overabundance in many settings.
Although atmospheric nitrogen gas is abundant, the gas is neither reactive
nor utilized by most plants. Reactive nitrogen, in nitrate and ammonia
fertilizers, is utilized by plants at some rate. However, excessive nutrients
(not utilized) are often washed into drainage ways, streams, and rivers
during rainfall and storm events. High N and P levels in surface water
runoff have the effect of dramatically increasing algae growth downstream
due to eutrophic conditions. The algal blooms have the unwanted effect of
strong decreases in dissolved oxygen, which is needed for survival of fish
and other aquatic life. Enhanced algae growth can thus disrupt normal
functioning of the ecosystem and cause what are known as "dead zones"
(see Figure Aquatic Dead Zones). The waters may locally become cloudy
and colored a shade of green, brown, or red. Eutrophication can occur
naturally, but it has been greatly enhanced due to the use of fertilizers. As a
result of eutrophication, many coastal waters contain increasingly
problematic dead zones where major rivers discharge nutrient-rich
agricultural runoff or poorly treated sewage and wastewater (e.g. Gulf of
Mexico, Chesapeake Bay, Baltic Sea, East China Sea) (see Figure Aquatic
Dead Zones). This issue is of great importance because the dead zones are
near inhabited coastlines with commercially and ecologically vital aquatic
life.
Eutrophication and
accumulation of algae.
Aquatic Dead Zones. The red circles show the size of many of our
planet's dead (hypoxia) zones, whereas the plain black dots are dead
zones of unknown size. Darker blue colors show high concentrations
of particulate organic matter, an indication of overly fertile waters
(high in N and P). Most dead zones occur in downriver of agricultural
areas (with overused fertilizer) or areas of high population density
with poorly treated wastewater. Source: NASA Earth Observatory via
Wikimedia Commons and Lamiot via Wikimedia Commons.
One of the most notorious dead zones (second to the Baltic Sea) is an 8,500
square mile region in the Gulf of Mexico (see Figure Aquatic Dead
Zones). The Mississippi River dumps high-nutrient runoff from its drainage
basin that includes vast agricultural lands in the American Midwest.
Increased algal growth produced by these nutrients has affected important
shrimp fishing grounds in the Gulf. The primary source of the nutrients is
the heavily tile-drained areas of farmland in the Midwest corn and soybean
belt (SW Minnesota, N Iowa, NE Illinois, N Indiana and NW Ohio).
Improved soil drainage systems over the past century or more have allowed
for effective transport of nitrate compounds as stormwater runoff into
drainage basins (Ohio River, Wabash River, Illinois River, Missouri River,
etc.) that feed into the Mississippi River. In other words, the same drainage
tiles that allow for the agricultural benefit of having rich
bottomland/wetland soils in production, have the disadvantage of increased
and more rapid movements of nitrate solutes to the Gulf of Mexico. Such
large-scale problems, across state governmental boundaries, can only be
fully addressed in the future with a national system of incentives,
regulations, or laws.
In addition to fertilizers, Nitrogen inputs to watersheds can also include
atmospheric deposition, livestock waste, and sewage, but nitrogen fertilizers
comprise a significant majority of the input to monitored streams,
particularly in springtime when much fertilizer is applied. Possible
solutions to this problem include encouraging farmers to apply a more
limited quantity of fertilizer in the spring (only as much as necessary),
rather than in the fall, to allow for considerably less time for stormwater or
meltwater runoff. Other solutions include maintaining cover crops, or
restoring wetlands in key locations to contain nitrate losses. An overall
strategy that limits the excess capacity of nutrients can simultaneously
benefit farmers (by limiting cost), the ecology of stream watersheds and
coastal ecosystems (also locally stressed by oil spills and other pollution).
Over the long term, more efforts will need to be made in the Mississippi
River Basin, and globally in similarly stressed agricultural or urban
watersheds (see Figure Aquatic Dead Zones), to improve the health and
sustainability of our soil, land, and aquatic ecosystems.
Review Questions
Exercise:
Problem: What is the importance of soil to our society today?
Exercise:
Problem:
How has human activity changed the physical, chemical, or biological
character of native soil?
Exercise:
Problem:
What practices can be used to improve the long-term sustainability of
soil health?
Further Reading
Hassett, J.J. & Banwart, W.L. (1992). Soils and Their Environment. New
Jersey: Prentice-Hall.
Birkeland, P.W. (1999). Soils and Geomorphology. London: Oxford
University Press.
A wealth of information may be obtained from your local county soil report
(USDA) or online, including detailed interactive soil maps, along with
useful data concerning soil types and their physical and chemical properties
(useful for home owners, in construction, land-use planning, agriculture,
etc.).
Physical Resources: Water, Pollution, and Minerals - Chapter Introduction
In this module, the Chapter "Physical Resources: Water, Pollution, and
Minerals" is introduced.
Introduction
Water, air, and food are the most important natural resources to people.
Humans can live only a few minutes without oxygen, about a week without
water, and about a month without food. Water also is essential for our
oxygen and food supply. Plants, which require water to survive, provide
oxygen through photosynthesis and form the base of our food supply. Plants
grow in soil, which forms by weathering reactions between water and rock.
Water is the most essential compound for Earth’s life in general. Human
babies are approximately 75% water and adults are 50-60% water. Our
brain is about 85% water, blood and kidneys are 83% water, muscles are
76% water, and even bones are 22% water. We constantly lose water by
perspiration; in temperate climates we should drink about 2 quarts of water
per day and people in hot desert climates should drink up to 10 quarts of
water per day. Loss of 15% of body-water usually causes death. Earth is
truly the “Water Planet” (see Figure Planet Earth from Space). The
abundance of water on Earth distinguishes us from other bodies in the solar
system. About 70% of Earth's surface is covered by oceans and
approximately half of Earth's surface is obscured by clouds at any time.
There is a very large volume of water on our planet, about 1.4 billion cubic
kilometers (km3) (330 million cubic miles) or about 53 billion gallons per
person on Earth. All of Earth’s water could cover the United States to a
depth of 145 km (90 mi). From a human perspective, the problem is that
over 97% of it is seawater, which is too salty to drink or use for irrigation.
The most commonly used water sources are rivers and lakes, which contain
less than 0.01% of the world’s water!
Planet Earth from Space Source: Created by
Marvel, based on a Nasa image via Wikimedia
Commons
One of our most important environmental goals is to provide a clean,
sufficient, and sustainable water supply for the world. Fortunately, water is
a renewable resource, and it is difficult to destroy. Evaporation and
precipitation combine to replenish our fresh water supply constantly and
quickly; however, water availability is complicated by its uneven
distribution over the Earth. Arid climate and densely populated areas have
combined in many parts of the world to create water shortages, which are
projected to worsen significantly in the coming years. Human activities
such as water overuse and water pollution have compounded the water
crisis that exists today. Hundreds of millions of people lack access to safe
drinking water, and billions of people lack access to improved sanitation as
simple as a pit latrine. As a result, nearly two million people die every year
from diarrheal diseases and 90% of those deaths occur among children
under the age of 5. Most of these are easily prevented deaths.
Although few minerals are absolutely essential for human life, the things
that define modern society require a wide range of them: iron ore for steel,
phosphate minerals for fertilizer, limestone rock for concrete, rare earth
elements for night-vision goggles and phosphors in computer monitors, and
lithium minerals for batteries in our laptops, cell phones, and electric cars.
As global population grows and emerging large economies expand, we will
face a crisis in the supply of many important minerals because they are
nonrenewable, which is to say we consume them far more quickly than
nature creates them. As we consume minerals from larger and lower grade
mineral deposits there will be greater environmental impacts from mineral
mining and processing. The impending mineral crisis may be more
challenging to address than the water crisis.
This chapter introduces basic principles in water supply, water pollution,
and mineral resources. The emphasis, however, is on environmental issues
and sustainable solutions for each problem.
Water Cycle and Fresh Water Supply
In this module, water reservoirs and water cycles are described, the
principles controlling groundwater resources are presented, the causes and
effects of depletion in different water reservoir are given, and solutions to
the water supply crisis are discussed.
Learning Objectives
After reading this module, students should be able to
¢ understand how the water cycle operates
e understand the principles controlling groundwater resources and how
they also can affect surface water resources
e know the causes and effects of depletion in different water reservoirs
e understand how we can work toward solving the water supply crisis
Water Reservoirs and Water Cycle
Water is the only substance that occurs naturally on earth in three forms:
solid, liquid and gas. It is distributed in various locations, called water
reservoirs. The oceans are by far the largest of the reservoirs with about
97% of all water but that water is too saline for most human uses (see
Figure Earth's Water Reservoirs). Ice caps and glaciers are the largest
reservoirs of fresh water but this water is inconveniently located, mostly in
Antarctica and Greenland. Shallow groundwater is the largest reservoir of
usable fresh water. Although rivers and lakes are the most heavily used
water resources, they represent only a tiny amount of the world’s water. If
all of world's water was shrunk to the size of 1 gallon, then the total amount
of fresh water would be about 1/3 cup, and the amount of readily usable
fresh water would be 2 tablespoons.
Distribution of Earths’s Water
Atmospheric water
0.22%
Freshwater — Biological water
2.5% 0.22%
Rivers 0.46%
Swamps and
marshes
2.53%
Soil moisture
3.52%
All Water on Earth
A :
Water usable by humans 1%
Total global Freshwater Surface water and
water other freshwater
ra
Lakes 0.86% Rivers 0.02%
Earth's Water Reservoirs Bar chart Distribution of Earth’s water
including total global water, fresh water, and surface water and other
fresh water and Pie chart Water usable by humans and sources of
usable water. Source: United States Geographical Survey Igor
Skiklomanov's chapter "World fresh water resources" in Peter H.
Gleick (editor), 1993, Water in Crisis: A Guide to the World's Fresh
Water Resources
The water cycle shows the movement of water through different reservoirs,
which include oceans, atmosphere, glaciers, groundwater, lakes, rivers, and
biosphere (see Figure The Water Cycle). Solar energy and gravity drive the
motion of water in the water cycle. Simply put, the water cycle involves
water moving from the ocean to the atmosphere by evaporation, forming
clouds. From clouds, it falls as precipitation (rain and snow) on both water
and land, where it can move in a variety of ways. The water on land can
either return to the ocean by surface runoff (unchannelized overland flow),
rivers, glaciers, and subsurface groundwater flow, or return to the
atmosphere by evaporation or transpiration (loss of water by plants to the
atmosphere).
suae Vater, Gycle
inde snow 3 1 orage in the atmos
ae 7 ater storage in the at phere
. / Oe Sublimation
recipitatio tT Evapotranspiration
ZA
Evaporation
- ,
<a U.S. Dépa thee
Ground-water storage —- U.S. Geologi
http://ga.water.usgs.gov/edu/watercycle.html
The Water Cycle Arrows depict movement of water to different
reservoirs located above, at, and below Earth’s surface. Source: United
States Geological Survey
An important part of the water cycle is how water varies in salinity, which
is the abundance of dissolved ions in water. Ocean water is called salt water
because it is highly saline, with about 35,000 mg of dissolved ions per liter
of seawater. Evaporation (where water changes from liquid to gas at
ambient temperatures) is a distillation process that produces nearly pure
water with almost no dissolved ions. As water vaporizes, it leaves the
dissolved ions in the original liquid phase. Eventually, condensation
(where water changes from gas to liquid) forms clouds and sometimes
precipitation (rain and snow). After rainwater falls onto land, it dissolves
minerals, which increases its salinity. Most lakes, rivers, and near-surface
groundwater have a relatively low salinity and are called fresh water. The
next several sections discuss important parts of the water cycle relative to
fresh water resources.
Primary Fresh Water Resources: Precipitation
Precipitation is a major control of fresh water availability, and it is unevenly
distributed around the globe (see Figure World Rainfall Map). More
precipitation falls near the equator, and landmasses there are characterized
by a tropical rainforest climate. Less precipitation tends to fall near 20—30°
north and south latitude, where the world’s largest deserts are located.
These rainfall and climate patterns are related to global wind circulation
cells. The intense sunlight at the equator heats air, causing it to rise and
cool, which decreases the ability of the air mass to hold water vapor and
results in frequent rainstorms. Around 30° north and south latitude,
descending air conditions produce warmer air, which increases its ability to
hold water vapor and results in dry conditions. Both the dry air conditions
and the warm temperatures of these latitude belts favor evaporation. Global
precipitation and climate patterns are also affected by the size of continents,
major ocean currents, and mountains.
SSS SS Sens Nh SSE an SE SESS SSS
Sy Average Annual precipitation mm. [in.] .
“al m 3000 [120] 2000 [80] 1000 (40) (§500 (20) 250 [10] [below 250
World Rainfall Map The false-color map above shows the amount of
rain that falls around the world. Areas of high rainfall include Central
and South America, western Africa, and Southeast Asia. Since these
areas receive so much rainfall, they are where most of the world's
rainforests grow. Areas with very little rainfall usually turn into
deserts. The desert areas include North Africa, the Middle East,
western North America, and Central Asia. Source: United States
Geological Survey Earth Forum, Houston Museum Natural Science
Surface Water Resources: Rivers, Lakes, Glaciers
Flowing water from rain and melted snow on land enters river channels by
surface runoff (see Figure Surface Runoff) and groundwater seepage (see
Figure Groundwater Seepage). River discharge describes the volume of
water moving through a river channel over time (See Figure River
Discharge). The relative contributions of surface runoff vs. groundwater
seepage to river discharge depend on precipitation patterns, vegetation,
topography, land use, and soil characteristics. Soon after a heavy rainstorm,
river discharge increases due to surface runoff. The steady normal flow of
river water is mainly from groundwater that discharges into the river.
Gravity pulls river water downhill toward the ocean. Along the way the
moving water of a river can erode soil particles and dissolve minerals,
creating the river’s load of moving sediment grains and dissolved ions.
Groundwater also contributes a large amount of the dissolved ions in river
water. The geographic area drained by a river and its tributaries is called a
drainage basin. The Mississippi River drainage basin includes
approximately 40% of the U.S., a measure that includes the smaller
drainage basins (also called watersheds), such as the Ohio River and
Missouri River that help to comprise it. Rivers are an important water
resource for irrigation and many cities around the world. Some of the
world’s rivers that have had international disputes over water supply
include the Colorado (Mexico, southwest U.S.), Nile (Egypt, Ethiopia,
Sudan), Euphrates (Iraq, Syria, Turkey), Ganges (Bangladesh, India), and
Jordan (Israel, Jordan, Syria).
Surface Runoff
Surface runoff, part of
overland flow in the
water cycle Source:
James M. Pease at
Wikimedia Commons
Groundwater Seepage Groundwater seepage can be
seen in Box Canyon in Idaho, where approximately
10 cubic meters per second of seepage emanates from
its vertical headwall. Source: NASA
River Discharge Colorado River, U.S.. Rivers are part of
overland flow in the water cycle and an important surface
water resource. Source: Gonzo fan2007 at Wikimedia
Commons
Lakes can also be an excellent source of fresh water for human use. They
usually receive water from surface runoff and groundwater discharge. They
tend to be short-lived on a geological time-scale because they are constantly
filling in with sediment supplied by rivers. Lakes form in a variety of ways
including glaciation (Great Lakes, North America, See Figure Great Lakes
from Space), recent tectonic uplift (Lake Tanganyika, Africa), and volcanic
eruptions (Crater Lake, Oregon). People also create artificial lakes
(reservoirs) by damming rivers. Large changes in climate can result in
major changes in a lake’s size. As Earth was coming out of the last Ice Age
about fifteen thousand years ago, the climate in the western U.S. changed
from cool and moist to warm and arid, which caused more than100 large
lakes to disappear. The Great Salt Lake in Utah is a remnant of a much
larger lake called Lake Bonneville.
Great Lakes from Space The Great Lakes hold 21% of the world's
unaee fresh water. Lakes a are an Me ey water resource.
Although glaciers represent the largest reservoir of fresh water, they
generally are not used as a water source because ney are wocated too far
from most people (see Figure Mountain Glacie Ar 1a). Melting
glaciers do provide a natural source of river water and pocereens During
the last Ice Age there was as much as 50% more water in glaciers than there
is today, which caused sea level to be about 100 m lower. Over the past
century, sea level has been rising in part due to melting glaciers. If Earth’s
climate continues to warm, the melting glaciers will cause an additional rise
in sea level.
Mountain Glacier in Argentina Glaciers are the largest reservoir of
fresh water but they are not used much as a water resource directly by
society because of their distance from most people. Source: Luca
Galuzzi - www.galuzzi.it
Groundwater Resources
Although most people in the U.S. and the world use surface water,
groundwater is a much larger reservoir of usable fresh water, containing
more than 30 times more water than rivers and lakes combined.
Groundwater is a particularly important resource in arid climates, where
surface water may be scarce. In addition, groundwater is the primary water
source for rural homeowners, providing 98% of that water demand in the
U.S.. Groundwater is water located in small spaces, called pore space,
between mineral grains and fractures in subsurface earth materials (rock or
sediment, i.e., loose grains). Groundwater is not located in underground
rivers or lakes except where there are caves, which are relatively rare.
Between the land surface and the depth where there is groundwater is the
unsaturated zone, where pore spaces contain only air and water films on
mineral grains (see Figure Subsurface Water Terminology).|[ footnote |
Below the unsaturated zone is the saturated zone, where groundwater
completely fills pore spaces in earth materials. The interface between the
unsaturated zone and saturated zone is the water table. Most groundwater
originates from rain or snowmelt, which infiltrates the ground and moves
downward until it reaches the saturated zone. Other sources of groundwater
include seepage from surface water (lakes, rivers, reservoirs, and swamps),
surface water deliberately pumped into the ground, irrigation, and
underground wastewater treatment systems, i.e., septic tanks. Recharge
areas are locations where surface water infiltrates the ground rather than
running off into rivers or evaporating. Wetlands and flat vegetated areas in
general are excellent recharge areas.
Groundwater is the name for water in the saturated zone and soil moisture
describes water in the unsaturated zone. Therefore, groundwater is the
underground water resource used by society but soil moisture is the
principal water supply for most plants and is an important factor in
agricultural productivity.
Sur face water
Water (not ground water) held by molecular attraction
surrounds surfaces of rock particles
All openings below water table
full of ground water
Subsurface Water Terminology Groundwater in pore spaces and
fractures of earth materials, saturated zone, unsaturated zone, and
water table, which follows land surface but in a more subdued way.
Source: United States Geological Survey
Groundwater is in constant motion due to interconnection between pore
spaces. Porosity is the percentage of pore space in an earth material and it
gives a measure of how much groundwater an earth material can hold.
Permeability is a measure of the speed that groundwater can flow through
an earth material, and it depends on the size and degree of interconnection
among pores. An earth material that is capable of supplying groundwater
from a well at a useful rate—i.e., it has relatively high permeability and
medium to high porosity—is called an aquifer. Examples of aquifers are
earth materials with abundant, large, well-connected pore spaces such as
sand, gravel, uncemented sandstone, and any highly fractured rock. An
earth material with low hydraulic conductivity is an aquitard. Examples of
aquitards include clay, shale (sedimentary rock with abundant clay), and
igneous and metamorphic rock, if they contain few fractures.
As discussed above, groundwater flows because most earth materials near
the surface have finite (nonzero) porosity and permeability values. Another
reason for groundwater movement is that the surface of the water table
commonly is not completely flat but mimics the topography of the land
surface, especially in humid climates. There is "topography" to the water
table because groundwater moves slowly through rock and soil, so it builds
up in higher elevation areas. In fact, when groundwater flows slowly
through aquitards and deep underground, it can take many thousands of
years to move relatively short distances. An unconfined aquifer has no
aquitard above it and, therefore, it is exposed to the atmosphere and surface
waters through interconnected pores (See Figure Flowing Groundwater).
In an unconfined aquifer, groundwater flows because of gravity to lower
water table levels, where it eventually may discharge or leave the
groundwater flow system. Discharge areas include rivers, lakes, swamps,
reservoirs, water wells, and springs (see Figure Fatzael Springs in Jordan
Valley). Springs are rivers that emerge from underground due to an abrupt
intersection of the land surface and the water table caused by joints, caves,
or faults that bring permeable earth materials to the surface. A confined
aquifer is bounded by aquitards below and above, which prevents recharge
from the surface immediately above. Instead, the major recharge occurs
where the confined aquifer intercepts the land surface, which may be a long
distance from water wells and discharge areas (see Figure Schematic Cross
Section of Aquifer Types). Confined aquifers are commonly inclined away
from recharge areas, so groundwater in a confined aquifer is under greater-
than-atmospheric pressure due to the weight of water in the upslope
direction. Similar to river discharge, groundwater discharge describes the
volume of water moving through an aquifer over time. Total groundwater
discharge depends on the permeability of the earth material, the pressure
that drives groundwater flow, and the size of the aquifer. It is important to
determine groundwater discharge to evaluate whether an aquifer can meet
the water needs of an area.
DISCHARGE AREA
a
—_ J Ph — “
1s | be
Und And
Flowing Groundwater Blue lines show the direction of
groundwater in unconfined aquifers, confined aquifers, and
confining beds. Deep groundwater moves very slowly
especially through low permeability layers.Source: United
States Geological Survey
Fatzael Springs in Jordan Valley A spring is a river that emerges
from underground due to an abrupt intersection of the water table with
the land surface such as alongside a hill. Source: Hanay at Mediawiki
Commons
Recharge
Potentiometric
surface Flowing Perched
F Water table
artesian ;
water i well Artesian Ground
Se ik We surface
{ (am —
Modified after Harlan and others, 1989
Schematic Cross Section of Aquifer Types This figure shows
different types of aquifers and water wells, including unconfined
aquifer, confined aquifer, water table well, artesian well, and flowing
artesian well. Point of triangle is water level in each well and water
table in other parts of figure. Water level in artesian well is at
potentiometric surface and above local water table (dashed blue line)
due to extra pressure on groundwater in confined aquifer. Water in
flowing artesian well moves above land surface. Source: Colorado
Geological Survey
Most shallow water wells are drilled into unconfined aquifers. These are
called water table wells because the water level in the well coincides with
the water table (See Figure Schematic Cross Section of Aquifer Types).
90% of all aquifers for water supply are unconfined aquifers composed of
sand or gravel. To produce water from a well, you simply need to drill a
hole that reaches the saturated zone and then pump water to the surface.
Attempting to pump water from the unsaturated zone is like drinking root
beer with a straw immersed only in the foam at the top.
To find a large aquifer for a city, hydrogeologists (geologists who specialize
in groundwater) use a variety of information including knowledge of earth
materials at the surface and sub-surface as well as test wells. Some people
search for water by dowsing, where someone holds a forked stick or wire
(called a divining rod) while walking over an area. The stick supposedly
rotates or deflects downward when the dowser passes over water.
Controlled tests show that a dowser's success is equal to or less than
random chance. Nevertheless, in many areas water wells are still drilled on
dowser’s advice sometimes for considerable money. There is no scientific
basis to dowsing.
Wells into confined aquifers typically are deeper than those into unconfined
aquifers because they must penetrate a confining layer. The water level in a
well drilled into a confined aquifer, which is an artesian well, (see Figure
Schematic Cross Section of Aquifer Types), moves above the local water
table to a level called the potentiometric surface because of the greater
pressure on the groundwater. Water in a flowing well (see Figure A
Flowing Well) moves all of the way to the land surface without pumping.
A Flowing Well Flowing artesian well where water
moves above the land surface due to extra pressure
on the groundwater in a confined aquifer. Source:
A confined aquifer tends to be depleted from groundwater pumping more
quickly than an unconfined aquifer, assuming similar aquifer properties and
precipitation levels. This is because confined aquifers have smaller recharge
areas, which may be far from the pumping well. Conversely, an unconfined
aquifer tends to be more susceptible to pollution because it is hydrologically
connected to the surface, which is the source of most pollution.
Groundwater and surface water (rivers, lakes, swamps, and reservoirs) are
strongly interrelated because both are part of the same overall resource.
Major groundwater removal (from pumping or drought) can lower the
levels of surface water and vice versa. We can define two types of streams:
gaining (effluent) streams and losing (influent) streams (see Figure
Interaction of Streams and Ground Water). Gaining streams tend to be
perennial (flow year round), are characteristic of humid climates, have the
water table sloping towards the river, and therefore gain water from
groundwater discharge. Losing streams tend to be ephemeral (flow only
after significant rain), are characteristic of arid climates, are located above
the water table (which slopes away from the river), and therefore lose water
to groundwater recharge. Pollution that is dumped into a losing stream will
tend to move into the ground and could also contaminate local groundwater.
A
GAINING STREAM
LOSING STREAM
°
LOSING STREAM THAT IS DISCONNECTED
FROM THE WATER TABLE
Flow Girection
Interaction of Streams and
Ground Water A) Gaining
stream where water table
slopes toward river and
groundwater discharges into
river, B) Losing stream
where water table slopes
away from river and river
water discharges into
groundwater, C) Losing
stream where water table is
separated from and below
river. Source: United States
Geological Survey
Water Use in the U.S. and World
People need water to produce the food, energy, and mineral resources they
use—commonly large amounts of it. Consider, for example, these
approximate water requirements for some things people in the developed
world use every day: one tomato = 3 gallons; one kilowatt-hour of
electricity (from a thermoelectric power plant) = 21 gallons; one loaf of
bread = 150 gallons; one pound of beef = 1,600 gallons; and one ton of steel
= 63,000 gallons. Human beings require only about 1 gallon per day to
survive, but a typical person in a U.S. household uses approximately 100
gallons per day, which includes cooking, washing dishes and clothes,
flushing the toilet, and bathing.
The water demand of an area is a function of the population and other uses
of water. There are several general categories of water use, including
offstream use, which removes water from its source, e.g., irrigation,
thermoelectric power generation (cooling electricity-producing equipment
in fossil fuel, nuclear, and geothermal power plants), industry, and public
supply; consumptive use, which is a type of offstream use where water
does not return to the surface water or groundwater system immediately
after use, e.g., irrigation water that evaporates or goes to plant growth; and
instream use, which is water used but not removed from a river, mostly for
hydroelectric power generation. The relative size of these three categories
are instream use >> offstream use > consumptive use. In 2005, the U.S.
used approximately 3,300 billion gallons per day for instream use, 410
billion gallons per day for offstream use, and 100 billion gallons per day for
consumptive use. The major offstream uses of that water were
thermoelectric (49%), irrigation (31%), public supply (11%), and industry
(4%, see Figure Trends in Total Water Withdrawals by_Water-use
Category, 1950-2005). About 15% of the total water withdrawals in the
U.S. in 2005 were saline water, which was used almost entirely for
thermoelectric power generation. Almost all of the water used for
thermoelectric power generation is returned to the river, lake, or ocean from
where it came but about half of irrigation water does not return to the
original source due to evaporation, plant transpiration, and loss during
transport, e.g., leaking pipes. Total withdrawals of water in the U.S. actually
decreased slightly from 1980 to 2005, despite a steadily increasing
population. This is because the two largest categories of water use
(thermoelectric and irrigation) stabilized or decreased over that time period
due to better water management and conservation. In contrast, public
supply water demand increased steadily from 1950 (when estimates began)
through 2005. Approximately 77% of the water for offstream use in the
U.S. in 2005 came from surface water and the rest was from groundwater
(see Figure ‘Trends in Source of Fresh Water Withdrawals in the U.S.
from 1950 to 2005).
=USGS
§§ Public supply
0) Rural domestic and livestock
6) Irrigation
{] Thermoelectric power
©) Other
—— Total withdrawals
WITHDRAWALS, IN BILLION GALLONS PER DAY
TOTAL WITHDRAWALS, IN BILLION GALLONS PER DAY
1950 1955 1960 1965 1970 1975 1980 1985 1990 1995 2000 2005
Trends in Total Water Withdrawals by Water-use Category, 1950-
2005 Trends in total water withdrawals in the U.S. from 1950 to 2005
by water use category, including bars for thermoelectric power,
irrigation, public water supply, and rural domestic and livestock. Thin
blue line represents total water withdrawals using vertical scale on
right. Source: United States Geological Survey
300
HAE
1950 1955 1960 1965 1970 1975 1980 1985 1990 1995 2000 2005
OS Groundwater ©) Total withdrawals
©) Surface water eee Population
S 5
o o
hm
So
oS
Population, in millions
=
So
Oo
~
a
Freshwater withdrawals, in billion gallons per day
Trends in Source of Fresh Water Withdrawals in the U.S. from
1950 to 2005 Trends in source of fresh water withdrawals in the U.S.
from 1950 to 2005, including bars for surface water, groundwater, and
total water. Red line gives U.S. population using vertical scale on
right. Source: United States Geological Survey
In contrast to trends in the U.S., global total water use is steadily increasing
at arate greater than world population growth (see Figure Trends in World
Water Use from 1900 to 2000 and Projected to 2025). During the
twentieth century global population tripled and water demand grew by a
factor of six. The increase in global water demand beyond the rate of
population growth is due to improved standard of living without an offset
by water conservation. Increased production of goods and energy entails a
large increase in water demand. The major global offstream water uses are
irrigation (68%), public supply (21%), and industry (11%).
Cubic km per year Forecast Forecast
3 200
7 =! ee
2 400 | ELL
2000 + | Pel ii ii
| ss Ee] Bee
1 200
800
400
nt 1 be ae -—
1900 1925 1950 1975 2000 2025 1900 1925 1950 1975 2000 2025 1900 1925 1950 1975 2000 2025
cca Extraction Ea Extraction Ea Extraction
I) Consumption HO) Consumption I) Consumption
The grey band represents the difference between the amount of water extracted and that actually
consumed. Water may be extracted, used, recycled (or returned to rivers or aquifers) and reused
several times over. Consumption is final use of water, after which it can no longer be reused. That extractions have
increased at a much faster rate is an indication of how much more intensively we can now exploit water. Only a
fraction of water extracted is lost through evaporation.
Trends in World Water Use from 1900 to 2000 and Projected to
2025 For each water major use category, including trends for
agriculture, domestic use, and industry. Darker colored bar represents
total water extracted for that use category and lighter colored bar
represents water consumed (i.e., water that is not quickly returned to
surface water or groundwater system) for that use category. Source:
Igor A. Shiklomanow, State Hydrological Institute (SHI, St.
Petersburg) and United Nations Educational, Scientific and Cultural
Water Supply Problems: Resource Depletion
As groundwater is pumped from water wells, there usually is a localized
drop in the water table around the well called a cone of depression (see
Figure Formation of a Cone of Depression around a Pumping Water
Well). When there are a large number of wells that have been pumping
water for a long time, the regional water table can drop significantly. This is
called groundwater mining, which can force the drilling of deeper, more
expensive wells that commonly encounter more saline groundwater. The
occurrence of mining does not mean that groundwater will never be
recharged, but in many cases the recharge rate is negligible on a human
time-scale. Confined aquifers are more susceptible to groundwater mining
due to their limited recharge areas. Urban development usually worsens
groundwater mining because natural recharge rates drop with the
proliferation of impermeable pavement, buildings, and roads. Extensive
groundwater pumping around Chicago has created a gigantic cone of
depression there. Because the water table dropped up to 250 m (800 ft) in
the area (see Figure Drop in Water Table in a Confined Aquifer in the
Area of Chicago, Illinois and Milwaukee, Wisconsin, U.S. from 1864 -
1980), many local public water suppliers have switched to Lake Michigan
water. Chicago is fortunate to have a large alternate supply of fresh water;
many arid locations don’t have that luxury. Other places where groundwater
mining is a serious problem include the High Plains (Ogallala Aquifer) and
the Desert Southwest of the U.S., Mexico, the Middle East, India, and
China. Rivers, lakes, and artificial lakes (reservoirs) can also be depleted
due to overuse. Some large rivers, such as the Colorado in the U.S. and
Yellow in China, run dry in some years. The case history of the Aral Sea
discussed below involves depletion of a lake. Finally, glaciers are being
depleted due to accelerated melting associated with global warming over
the past century.
Formation of a cone of
depression in the water table
After heavy
pumping
Formation of a Cone of Depression around a Pumping Water Well
Source: Fayette County Groundwater Conservation District, TX
Base forn US. Geological Survey 12,000,000 Digit Data
Albers Equal-area Conic Projection
Standard paratiels 33° and 45°, central merician -a°
EXPLANATION
——700~— Line of equal water-level decline, 1864-1980—Dashed
where approximate. Interval, in feet, is variable
sc omme Major ground-water divide
Drop in Water Table in a
Confined Aquifer in the Area
of Chicago, Illinois and
Milwaukee, Wisconsin, U.S.
from 1864 - 1980 Source:
United States Geological
Survey
Another water resource problem associated with groundwater mining is
saltwater intrusion, where overpumping of fresh water aquifers near ocean
coastlines causes saltwater to enter fresh water zones. Saltwater intrusion is
a significant problem in many coastal areas of the U.S. including Long
Island, New York; Cape Cod, Massachusetts; and southeastern and Gulf
Coastal states. The drop of the water table around a cone of depression in an
unconfined aquifer can change the regional groundwater flow direction,
which could send nearby pollution toward the pumping well instead of
away from it. Finally, problems of subsidence (gradual sinking of the land
surface over a large area) and sinkholes (rapid sinking of the land surface
over a small area) can develop due to a drop in the water table.
The Water Supply Crisis
The water crisis refers to a global situation where people in many areas
lack access to sufficient water or clean water or both. This section describes
the global situation involving water shortages, also called water stress. The
next section covers the water crisis involving water pollution. Figure
Countries Facing Water Stress in 1995 and Projected in 2025 shows
areas of the world experiencing water stress as defined by a high percentage
of water withdrawal compared to total available water. Due to population
growth the 2025 projection for global water stress is significantly worse
than water stress levels in 1995. In general, water stress is greatest in areas
with very low precipitation (major deserts) or large population density (e.g.,
India) or both. Future global warming could worsen the water crisis by
shifting precipitation patterns away from humid areas and by melting
mountain glaciers that recharge rivers downstream. Melting glaciers will
also contribute to rising sea level, which will worsen saltwater intrusion in
aquifers near ocean coastlines. Compounding the water crisis is the issue of
social injustice; poor people generally get less access to clean water and
commonly pay more for water than wealthy people.
Water withdrawal as a percentage of total available water
HB more than 40% — IP from 20 % to 10 %
| from 40 % to 20 % [I less than 10 %
Countries Facing Water Stress in 1995 and Projected in 2025
Water stress is defined as having a high percentage of water
withdrawal compared to total available water in the area. Source:
Philippe Rekacewicz (Le Monde diplomatique), February 2006
According to a 2006 report by the United Nations Development
Programme, in 2005, 700 million people (11% of the world’s population)
lived under water stress with a per capita water supply below 1,700
m?/year[ footnote] (Watkins, 2006). Most of them live in the Middle East
and North Africa. By 2025, the report projects that more than 3 billion
people (about 40% of the world’s population) will live in water-stressed
areas with the large increase coming mainly from China and India. The
water crisis will also impact food production and our ability to feed the
ever-growing population. We can expect future global tension and even
conflict associated with water shortages and pollution. Historic and future
areas of water conflict include the Middle East (Euphrates and Tigris River
conflict among Turkey, Syria, and Iraq; Jordan River conflict among Israel,
Lebanon, Jordan, and the Palestinian territories), Africa (Nile River conflict
among Egypt, Ethiopia, and Sudan), Central Asia (Aral Sea conflict among
Kazakhstan, Uzbekistan, Turkmenistan, Tajikistan, and Kyrgyzstan), and
south Asia (Ganges River conflict between India and Pakistan).
Although 1,700 m°/year sounds like a lot of water for every person, it is the
minimum amount that hydrologists consider is needed to grow food,
support industry, and maintain the environment in general.
Sustainable Solutions to the Water Supply Crisis?
The current and future water crisis described above requires multiple
approaches to extending our fresh water supply and moving towards
sustainability. Some of the longstanding traditional approaches include
dams and aqueducts. Reservoirs that form behind dams in rivers can
collect water during wet times and store it for use during dry spells (see
Figure Hoover Dam, Nevada, U.S.). They also can be used for urban water
supplies. New York City has a large number of reservoirs and controlled
lakes up to 200 km away to meet the water demands of its large population.
Other benefits of dams and reservoirs are hydroelectricity, flood control,
and recreation. Some of the drawbacks are evaporative loss of reservoir
water in arid climates, downstream river channel erosion, and impact on the
ecosystem including a change from a river to lake habitat and interference
with fish migration and spawning. Aqueducts can move water from where it
is plentiful to where it is needed (see Figure The California Aqueduct).
Southern California has a large and controversial network of aqueducts that
brings in water from the Sierra Nevada Mountains in the north, the valleys
in northern and central California, and the Colorado River to the east (see
Figure Map of California Aqueducts). Aqueducts can be controversial and
politically difficult especially if the water transfer distances are large. One
drawback is the water diversion can cause drought in the area from where
the water is drawn. For example, Owens Lake and Mono Lake in central
California began to disappear after their river inflow was diverted to the
Los Angeles aqueduct. Owens Lake remains almost completely dry, but
Mono Lake has recovered more significantly due to legal intervention.
Hoover Dam, Nevada, U.S. Hoover Dam,
Nevada, U.S.. Behind the dam is Lake Mead, the
largest reservoir in U.S.. White band reflects the
lowered water levels in the reservoir due to
drought conditions from 2000 - 2010. Source:
Cygnusloop99 at Wikimedia Commons
The California Aqueduct California Aqueduct in southern California,
U.S. Source: David Jordan at en.wikipedia
¥ Central Basin
Municipal Water District
California
Aqueducts
>
Los/Angeles
GentraliBasin
Senvice WIE
Map of California Aqueducts Map of
California aqueducts that bring water to
southern California from central and
northern California and from the
Colorado River to the east. Source:
Central Basin Municipal Water District
The Colorado River, probably the most exploited river in the U.S., has
many dams, some huge reservoirs, and several large aqueducts so that it can
provide large amounts of fresh water to 7 states in the arid southwestern
U.S. and Mexico. The primary use for the water is for a few large cities
(Las Vegas, Phoenix, and Tuscon) and irrigation. Allocation of Colorado
River water is strictly regulated. Fortunately, not all states use all of their
water allocation because the total amount of allocated water is more than
the typical Colorado River discharge. Colorado River water gets so saline
due to evaporation along its course that the U.S. was forced to build a
desalination plant near the border with Mexico so that it could be used for
drinking and irrigation. The wetlands of the Colorado River delta and its
associated ecosystem have been sadly degraded by the water overuse; some
years, no river flow even reaches the ocean.
One method that actually can increase the amount of fresh water on Earth is
desalination, which involves removing dissolved salt from seawater or
saline groundwater. There are several ways to desalinate seawater including
boiling, filtration, electrodialysis, and freezing. All of these procedures are
moderately to very expensive and require considerable energy input,
making the produced water much more expensive than fresh water from
conventional sources. In addition, the processes create highly saline
wastewater, which must be disposed of. Desalination is most common in
the Middle East, where energy from oil is abundant but water is scarce.
Conservation means using less water and using it more efficiently. Around
the home, conservation can involve both engineered features, such as high-
efficiency clothes washers and low-flow showers and toilets, as well as
behavioral decisions, such as growing native vegetation that require little
irrigation in desert climates, turning off the water while you brush your
teeth, and fixing leaky faucets. Rainwater harvesting involves catching
and storing rainwater for reuse before it reaches the ground. Efficient
irrigation is extremely important because irrigation accounts for a much
larger water demand than public water supply. Water conservation
Strategies in agriculture include growing crops in areas where the natural
rainfall can support them, more efficient irrigation systems such as drip
systems that minimize losses due to evaporation, no-till farming that
reduces evaporative losses by covering the soil, and reusing treated
wastewater from sewage treatment plants. Recycled wastewater has also
been used to recharge aquifers. There are a great many other specific water
conservation strategies. Sustainable solutions to the water crisis must use a
variety of approaches but they should have water conservation as a high
priority.
Review Questions
Exercise:
Problem:
What is the water cycle and why is it important to fresh water
resources?
Exercise:
Problem:
What are the relative merits of using surface water vs. groundwater as
a water resource?
Exercise:
Problem:
What should society learn from the case history of the Aral Sea?
Exercise:
Problem:
Why is society facing a crisis involving water supply and how can we
solve it?
References
Watkins, K. (2006). Beyond scarcity: Power, poverty and the global water
crisis. Human Development Report 2006, United Nations Development
Programme. Retrieved from http://hdr.undp.org/en/reports/global/hdr2006/
Glossary
aqueduct
An aqueduct is a water supply or navigable channel constructed to
convey water. In modern engineering, the term is used for any system
of pipes, ditches, canals, tunnels, and other structures used for this
purpose.
aquifer
Rock or sediment that is capable of supplying groundwater from a well
at a useful rate.
aquitard
Earth material with low hydraulic conductivity.
artesian well
Water well drilled into a confined aquifer where the water level in the
well moves above the local water table.
condensation
Change in the physical state of water where it goes from gas to liquid.
cone of depression
A localized drop in the water table around a pumping well.
confined aquifer
An aquifer that is bounded by aquitards below and above.
consumptive water use
A societal use of water that is a type of offstream use where water does
not return to the river or groundwater system immediately after use.
dam
A barrier built across a river to obstruct the flow of water.
desalination
Removing dissolved salt from seawater or saline groundwater.
discharge area
Location on Earth where groundwater leaves the groundwater flow
system.
drainage basin
Geographic area drained by a river and its tributaries.
evaporation
Where water changes from liquid to gas at ambient temperatures.
groundwater
Water located in small spaces between mineral grains and fractures in
subsurface rock or sediment.
groundwater mining
A depletion in groundwater resources caused by a large number of
water wells that pumped water for a long time.
instream water use
A societal use of water that does not remove it from its source.
offstream water use
A societal use of water that removes it from its source.
permeability
Measure of the speed that groundwater can flow through rock or
sediment.
pore space
Small spaces between mineral grains in subsurface rock or sediment.
porosity
Percentage of pore space in rock or sediment.
rainwater harvesting
Catching and storing rainwater for reuse before it reaches the ground.
recharge area
Location on Earth where surface water infiltrates into the ground
rather than runs off into rivers or evaporates.
reservoir
Large artificial lake used as a source of water.
river discharge
Volume of water moving through a river channel over time.
saltwater intrusion
Saltwater that enters an aquifer due to overpumping of freshwater
aquifers near ocean coastlines.
saturated zone
Subsurface area where groundwater completely fills pore spaces in
rock or sediment.
soil moisture
Water in the unsaturated zone.
spring
River that emerges from underground due to an abrupt intersection of
the water table with the land surface.
surface runoff
Unchannelized overland flow of water.
transpiration
Loss of water by plants to the atmosphere.
unconfined aquifer
Aquifer with no aquitard above it.
unsaturated zone
Subsurface area where pore spaces contain only air and water films on
mineral grains.
water conservation
Using less water and using it more efficiently
water crisis
A global situation where people in many areas lack access to sufficient
water or clean water or both.
water cycle
The continuous movement of water through water reservoirs located
on, above, and below Earth’s surface.
water reservoir (in water cycle)
General location on Earth where water is located including oceans,
atmosphere, glaciers, groundwater, lakes, rivers, and biosphere.
water table
Interface between the unsaturated zone and saturated zone.
water table well
Water well drilled into an unconfined aquifer where the water level in
the well coincides with the water table.
Case Study: The Aral Sea - Going, Going, Gone
The Aral Sea is a lake located east of the Caspian Sea between Uzbekistan
and Kazakhstan in central Asia (see Figure Map of Aral Sea Area). This
area is part of the Turkestan desert, which is the fourth largest desert in the
world; it is produced from a rain shadow effect by Afghanistan's high
mountains to the south. Due to the arid and seasonally hot climate there is
extensive evaporation and limited surface waters in general. Summer
temperatures can reach 60° C (140° F)! The water supply to the Aral Sea is
mainly from two rivers, the Amu Darya and Syr Darya, which carry
snowmelt from mountainous areas. In the early 1960s the then-Soviet
Union diverted the Amu Darya and Syr Darya Rivers for irrigation of one
of the driest parts of Asia to produce rice, melons, cereals, and especially
cotton. The Soviets wanted cotton or “white gold” to become a major
export. They were successful and today Uzbekistan is one of the world's
largest exporters of cotton. Unfortunately this action essentially eliminated
any river inflow to the Aral Sea and caused it to disappear almost
completely.
Map of Aral Sea Area Map
shows lake size in 1960 and
political boundaries of 2011.
Countries in yellow are at least
partially in Aral Sea drainage
basin. Source: Wikimedia
Commons
In 1960 Aral Sea was the fourth largest inland water body; only the Caspian
Sea, Lake Superior, and Lake Victoria were larger. Since then, it has
progressively shrunk due to evaporation and lack of recharge by rivers (see
Figure Shrinking Aral Sea Blue). Before 1965 the Aral Sea received 20—
60 km? of fresh water per year from rivers and by the early 1980s it
received none. By 2007 the Aral Sea shrank to about 10% of its original
size and its salinity increased from about 1% dissolved salt to about 10%
dissolved salt, which is 3 times more saline than seawater. These changes
caused an enormous environmental impact. A once thriving fishing industry
is dead as are the 24 species of fish that used to live there; the fish could not
adapt to the more saline waters. The current shoreline is tens of kilometers
from former fishing towns and commercial ports. Large fishing boats lie in
the dried up lakebed of dust and salt (see Figure An Abandoned Ship). A
frustrating part of the river diversion project is that many of the irrigation
canals were poorly built, allowing abundant water to leak or evaporate. An
increasing number of dust storms blow salt, pesticides, and herbicides into
nearby towns causing a variety of respiratory illnesses including
tuberculosis.
0 100 km Aral
———— $$
Kasachstan
Shrinking Aral Sea Blue area gives size of
Aral Sea in 1960, 1970, 1980, 1990, 2000,
2004, 2008, and 2009 Source: NordNordWest at
Wikimedia Commons
An Abandoned Ship This abandoned ship lies in a dried up lake bed
that was the Aral Sea near Aral, Kazakhstan Source: Staecker at
Wikimedia Commons
The wetlands of the two river deltas and their associated ecosystems have
disappeared. The regional climate is drier and has greater temperature
extremes due to the absence of moisture and moderating influence from the
lake. In 2003 some lake restoration work began on the northern part of the
Aral Sea and it provided some relief by raising water levels and reducing
salinity somewhat. The southern part of the Aral Sea has seen no relief and
remains nearly completely dry. The destruction of the Aral Sea is one of the
planet’s biggest environmental disasters and it is caused entirely by humans.
Lake Chad in Africa is another example of a massive lake that has nearly
disappeared for the same reasons as the Aral Sea. Aral Sea and Lake Chad
are the most extreme examples of large lakes destroyed by unsustainable
diversions of river water. Other lakes that have shrunk significantly due to
human diversions of water include the Dead Sea in the Middle East, Lake
Manchar in Pakistan, and Owens Lake and Mono Lake, both in California.
Water Pollution
In this module, the following topics will be covered: 1) water pollutants and
how they degrade water quality, 2) the lack of safe drinking water in some
parts of the world , 3) sewage treatment 4) the difficult process to remediate
groundwater pollution, and 5) solutions for the crisis involving water
pollution
Learning Objectives
After reading this module, students should be able to
e understand the major kinds of water pollutants and how they degrade
water quality
¢ understand how and why the lack of safe drinking water in some parts
of the world is a major problem
e know what sewage treatment does and why it is important
¢ know why it is more difficult to remediate groundwater pollution than
surface water pollution
¢ understand how we can work toward solving the crisis involving water
pollution
The Water Pollution Crisis
The Module Water Cycle and Fresh Water Supply described one aspect
of the global water crisis, the water shortages that afflict many arid and
densely populated areas. The global water crisis also involves water
pollution, because to be useful for drinking and irrigation, water must not
be polluted beyond certain thresholds. According to the World Health
Organization, in 2008 approximately 880 million people in the world (or
13% of world population) did not have access to improved (safe) drinking
water (World Health Statistics, 2010) (See Figure Proportion of
Population by Country Using Improved Drinking Water Sources in
2008). At the same time, about 2.6 billion people (or 40% of world
population) lived without improved sanitation (see Figure Proportion of
which is defined as having access to a public sewage system, septic tank, or
even a simple pit latrine. Each year approximately 1.7 million people die
from diarrheal diseases associated with unsafe drinking water, inadequate
sanitation, and poor hygiene, e.g., hand washing with soap. Almost all of
these deaths are in developing countries, and around 90% of them occur
among children under the age of 5 (see Figure Deaths by Country from
Hygiene in Children Less than 5 Years Old, 2004). Compounding the
water crisis is the issue of social justice; poor people more commonly lack
clean water and sanitation than wealthy people in similar areas. Globally,
improving water, sanitation, and hygiene could prevent up to 9% of all
disease and 6% of all deaths. In addition to the global waterborne disease
crisis, chemical pollution from agriculture, industry, cities, and mining
threatens global water quality. Some chemical pollutants have serious and
well-known health effects; however, many others have poorly known long-
term health effects. In the U.S. currently more than 40,000 water bodies fit
the definition of “impaired” set by EPA (See Figure Percentage of
Impaired Water Bodies in a Watershed by State in USA Based on US
EPA Data in 2000), which means they could neither support a healthy
ecosystem nor meet water quality standards. In Gallup public polls
conducted over the past decade Americans consistently put water pollution
and water supply as the top environmental concerns over issues such as air
pollution, deforestation, species extinction, and global warming.
a To ete Tor Eno ee ie | (Date Sow roid Peale Degancaten, Worle Healthy
sae juct of the Word Meath Cngancaten cont emang tet legal uate of any county teary oby ar aren ar ol bx autonben, ‘Mg Predatory: Phables Haakh lntlaamaiar
pore fe delat oh border oa boureliaray ested ae on ag represen eppeearmata ber de ean ber ahhh aed Gagne: Ind pemabor: bysterea jO05) Organizatens
are ray nol pel be kal epee Winall Hee Orpanciton, oh 00 Aan i
Proportion of Population by Country Using Improved Drinking
Water Sources in 2008 Improved drinking water sources, e.g.,
household connections, public standpipes, boreholes, protected dug
wells and springs, and rainwater collections, are defined as those more
likely to provide safe water than unimproved water sources, e.g.,
unprotected wells and springs, vendor-provided water, bottled water
(unless water for other uses is available from an improved source), and
tanker truck-provided water. Source: World Health Organization
Tha nares el awed haar rel at degra wed estat ug da Fry Rab deen cea ip Epon ahaha Tat Sige}: Wal Pai Dea ations World Health
a a pert ol oa Laid Higa Cerpamcy ation coecobamargy ed gad aed ag tion Mey iy a a ce a, Ug: Preedioctee, Piatie: Health bedvarraitent 2 ination
Premnang Be deleadabon of dy beedar or Burda Coste ling crs apn ragraneed apeneemmunds Boece Dear to af ard peg phe efor Sydeen (LES Orga .
thay rary ol pet oe Al agpeersae, ‘eee Haas Gepancaion (WHE) FH. ileaghts oeoerved
Proportion of Population by Country Using Improved Sanitation
Facilities in 2008 Improved sanitation facilities, e.g., connection to
public sewers or septic systems, pour-flush latrines, pit latrines, and
ventilated improved pit latrines, are defined as those more likely to be
sanitary than unimproved facilities, e.g., bucket latrines, public
latrines, and open pit latrines. Source: World Health Organization
o*
Deaths per 100 000 children
|__]o=100
[) 101-200
a si
Be i
<0
[-_] Data not arvaitatte
[1] Nict applicable
‘The bebarotharcar. rel rae. eta ated hen dbesagraatepe) woe oot Oh aps de tarry Ron petri fol ety operate eho carved Chats Sheraton, bed Manali Dirgearaziateh " ‘World Haale
on Bbw pad of the World laa Gegarataton concerreng the legal viatun of any country, bemiory, off of aren ot of oo tore, Allap Procectore Putte Hawt infcrsaiion Organization
a cmaning he deiméaton of 6 berber a bsurdanen Deded bras on mapa regreeet appa areata beceder Beau ter afachs and Gecgrapte: lefiomrution ‘Syutena (LETS) :
Waka ty ah et ok ll ge eve ‘eget al Spear apt, OHO S00) Allnghh oeerved
Deaths by Country from Diarrhea Caused by Unsafe Water,
Unimproved Sanitation, and Poor Hygiene in Children Less than 5
Years Old, 2004 Source: World Health Organization
Impaired
Waters-1998 ‘
(Updated Feb. 2000)
No Waters Listed
me <5%
Gy 5 - 10%
We 10-25%
Ma > 25%
Percentage of Impaired Water Bodies in a Watershed by State
in USA Based on US EPA Data in 2000 Map of watersheds
containing impaired water bodies from the U.S. Environmental
Protection Agency's 1998 list of impaired waters Source: U.S.
Geological Survey
Water Chemistry Overview
Compared to other molecules of similar molecular weight, water (H2O) has
unique physical properties including high values for melting and boiling
point, surface tension (water’s cohesion, or “stickiness”), and capacity to
dissolve soluble minerals, i.e., act as a solvent. These properties are related
to its asymmetrical structure and polar nature, which means it is electrically
neutral overall but it has a net positive charge on the side with the two
hydrogen atoms and a net negative charge on the oxygen side (see Figure
Structure of Water, Polar Charge of Water, and Hydrogen Bonds
between Water Molecules). This separation of the electrical charge within
a water molecule results in hydrogen bonds with other water molecules,
mineral surfaces (hydrogen bonding produces the water films on minerals
in the unsaturated zone of the subsurface), and dissolved ions (atoms with a
negative or positive charge). Many minerals and pollutants dissolve readily
in water because water forms hydration shells (spheres of loosely
coordinated, oriented water molecules) around ions.
Hydrogen
bonds
Structure of Water, Polar Charge of Water,
and Hydrogen Bonds between Water
Molecules Source: Michal Manas at
Wikimedia Commons
Any natural water contains dissolved chemicals; some of these are
important human nutrients, while others can be harmful to human health.
The abundance of a water pollutant is commonly given in very small
concentration units such as parts per million (ppm) or even parts per billion
(ppb). An arsenic concentration of 1 ppm means 1 part of arsenic per
million parts of water. This is equivalent to one drop of arsenic in 50 liters
of water. To give you a different perspective on appreciating small
concentration units, converting 1 ppm to length units is 1 cm (0.4 in) in 10
km (6 miles) and converting 1 ppm to time units is 30 seconds in a year.
Total dissolved solids (TDS) represent the total amount of dissolved
material in water. Average TDS (salinity) values for rainwater, river water,
and seawater are about 4 ppm, 120 ppm, and 35,000 ppm. As discussed in
Module Climate Processes; External and Internal Controls, the most
important processes that affect the salinity of natural waters are
evaporation, which distills nearly pure water and leaves the dissolved ions
in the original water, and chemical weathering, which involves mineral
dissolution that adds dissolved ions to water. Fresh water is commonly
defined as containing less than either 1,000 or 500 ppm TDS, but the US
Environmental Protection Agency (EPA) recommends that drinking water
not exceed 500 ppm TDS or else it will have an unpleasant salty taste.
Water Pollution Overview
Water pollution is the contamination of water by an excess amount of a
substance that can cause harm to human beings and the ecosystem. The
level of water pollution depends on the abundance of the pollutant, the
ecological impact of the pollutant, and the use of the water. Pollutants are
derived from biological, chemical, or physical processes. Although natural
processes such as volcanic eruptions or evaporation sometimes can cause
water pollution, most pollution is derived from human, land-based activities
(see Figure Water Pollution). Water pollutants can move through different
water reservoirs, as the water carrying them progresses through stages of
the water cycle (see Figure Sources of Water Contamination). Water
residence time (the average time that a water molecule spends in a water
reservoir) is very important to pollution problems because it affects
pollution potential. Water in rivers has a relatively short residence time, so
pollution usually is there only briefly. Of course, pollution in rivers may
simply move to another reservoir, such as the ocean, where it can cause
further problems. Groundwater is typically characterized by slow flow and
longer residence time, which can make groundwater pollution particularly
problematic. Finally, pollution residence time can be much greater than the
water residence time because a pollutant may be taken up for a long time
within the ecosystem or absorbed onto sediment.
Water Pollution Obvious water pollution in
the form of floating debris; invisible water
pollutants sometimes can be much more
harmful than visible ones. Source: Stephen
Codrington at Wikimedia Commons
Point-source contamination can ution spreads across the landscape
be traced to specific points of en overlooked as a major nonpoint
discharge from wastewater of pollution. Airborne nutrients and
treatment plants and factories or esticides can be transported far from their
from combined sewers. area of origin.
mre aye eae
" . soil and sediment
a transport considerable
amounts of some nutrients,
such as organic nitrogen and
phosphorus, and some
pesticides, such as DDT,
to rivers and streams.
SEEPAGE GROUND-WATER SEEPAGE
DISCHARGE
TO STREAMS
Sources of Water Contamination Sources of some water pollutants
and movement of pollutants into different water reservoirs of the water
cycle. Source: U.S. Geological Survey
Pollutants enter water supplies from point sources, which are readily
identifiable and relatively small locations, or nonpoint sources, which are
large and more diffuse areas. Point sources of pollution include animal
“factory” farms that raise a large number and high density of livestock such
as cows, pigs, and chickens (see Figure A Commercial Meat Chicken
Production House) and discharge pipes from a factories or sewage
treatment plants. Combined sewer systems that have a single set of
underground pipes to collect both sewage and storm water runoff from
streets for wastewater treatment can be major point sources of pollutants.
During heavy rain, storm water runoff may exceed sewer capacity, causing
it to back up and spilling untreated sewage into surface waters (see Figure
Combined Sewer System). Nonpoint sources of pollution include
agricultural fields, cities, and abandoned mines. Rainfall runs over the land
and through the ground, picking up pollutants such as herbicides, pesticides,
and fertilizer from agricultural fields and lawns; oil, antifreeze, car
detergent, animal waste, and road salt from urban areas; and acid and toxic
elements from abandoned mines. Then, this pollution is carried into surface
water bodies and groundwater. Nonpoint source pollution, which is the
leading cause of water pollution in the U.S., is usually much more difficult
and expensive to control than point source pollution because of its low
concentration, multiple sources, and much greater volume of water.
7a
Len we Ka a) eee
Se. SE 440s “ep
A Commercial Meat Chicken Production House This chicken
factory farm is a possible major point source of water pollution.
Source: Larry Rana at Wikimedia Commons
Dry Weather
a
iq
gor
Outfall pipe and storm Pion
to river
Sewer to POTW
Combined Sewer System A combined sewer system is a possible
major point source of water pollution during heavy rain due to
overflow of untreated sewage. During dry weather (and small storms),
all flows are handled by the publicly owned treatment works (POTW).
During large storms, the relief structure allows some of the combined
stormwater and sewage to be discharged untreated to an adjacent water
body. Source: U.S. Environmental Protection Agency at Wikimedia
Commons
Types of Water Pollutants
Oxygen-demanding waste is an extremely important pollutant to
ecosystems. Most surface water in contact with the atmosphere has a small
amount of dissolved oxygen, which is needed by aquatic organisms for
cellular respiration. Bacteria decompose dead organic matter (chemically
represented in a simplified way as CH»O) and remove dissolved oxygen
(O>) according to the following reaction:
Equation:
CH,O + Og + CO, + H2O
Too much decaying organic matter in water is a pollutant because it
removes oxygen from water, which can kill fish, shellfish, and aquatic
insects. The amount of oxygen used by aerobic (in the presence of oxygen)
bacterial decomposition of organic matter is called biochemical oxygen
demand (BOD). The major source of dead organic matter in most natural
waters is sewage; grass and leaves are smaller sources. An unpolluted water
body with respect to oxygen is a turbulent river that flows through a natural
forest. Turbulence continually brings water in contact with the atmosphere
where the O, content is restored. The dissolved oxygen content in such a
river ranges from 10 to 14 ppm Op», BOD is low, and clean-water fish, e.g.,
bass, trout, and perch dominate. A polluted water body with respect to
oxygen is a stagnant deep lake in an urban setting with a combined sewer
system. This system favors a high input of dead organic carbon from
sewage overflows and limited chance for water circulation and contact with
the atmosphere. In such a lake, the dissolved O, content is <5 ppm Os,
BOD is high, and low O,-tolerant fish, e.g., carp and catfish dominate.
Excessive plant nutrients, particularly nitrogen (N) and phosphorous (P),
are pollutants closely related to oxygen-demanding waste. Aquatic plants
require about 15 nutrients for growth, most of which are plentiful in water.
N and P are called limiting nutrients, because they usually are present in
water at low concentrations and therefore restrict the total amount of plant
growth. This explains why N and P are major ingredients in most fertilizer.
High concentrations of N and P from human sources (mostly agricultural
and urban runoff including fertilizer, sewage, and P-based detergent) can
cause cultural eutrophication, which involves the rapid growth of aquatic
plants, particularly algae, called an algal bloom. Thick mats of floating and
rooted green or sometimes red algae (see Figure Algal Bloom in River in
Sichuan, China) create water pollution, damage the ecosystem by clogging
fish gills and blocking sunlight, and damage lake aesthetics by making
recreation difficult and creating an eyesore. A small percentage of algal
species produce toxins that can kill fish, mammals, and birds, and may
cause human illness; explosive growths of these algae are called harmful
algal blooms (see Figure Harmful Algal Bloom). When the prolific algal
layer dies, it becomes oxygen-demanding waste, which can create very low
O> water (<~2 ppm O>), called hypoxia or dead zone because it causes
death to organisms that are unable to leave that environment. An estimated
50% of lakes in North America, Europe, and Asia are negatively impacted
by cultural eutrophication. In addition, the size and number of marine
hypoxic zones have grown dramatically over the past 50 years (see Figure
Aquatic Dead Zones), including a very large dead zone located offshore
Louisiana in the Gulf of Mexico. Cultural eutrophication and hypoxia are
difficult to combat, because they are caused primarily by nonpoint source
pollution, which is difficult to regulate, and N and P, which are difficult to
remove from wastewater.
Algal Bloom in River in Sichuan, China Algal
blooms can present problems for ecosystems and
human society. Source: Felix Andrews via Wikimedia
Commons
Harmful Algal Bloom Harmful algal bloom with deep red color.
Source: Kai Schumann via National Oceanic and Atmospheric
Administration
ad
eS = af = _ —S-- -_ ee eee tte yy
= 6 % —— -
Particulate Organic Carbon (eg /m') Population Density (persons)
a “
0 #23 9 100 200 $60 1,000 ' 10 100 1,000 10% 100%
Dead Zone Size (my)
nr ee ®
OL 4 10 100 tk 10%
Aquatic Dead Zones Zones of hypoxia shown as red circles. Black
dots show hypoxia zones of unknown size, brown shading shows
population density, and blue shading shows density of particulate
organic carbon, an indicator of organic productivity. Source: Robert
Simmon & Jesse Allen at NASA Earth Observatory via Wikimedia
Commons
Pathogens are disease-causing microorganisms, e.g., viruses, bacteria,
parasitic worms, and protozoa, which cause a variety of intestinal diseases
such as dysentery, typhoid fever, hepatitis, and cholera. Pathogens are the
major cause of the water pollution crisis discussed at the beginning of this
section. Unfortunately nearly a billion people around the world are exposed
to waterborne pathogen pollution daily and around 1.5 million children
mainly in underdeveloped countries die every year of waterborne diseases
from pathogens (see Figure Deaths by Country from Diarrhea Caused by
Less than 5 Years Old, 2004). Pathogens enter water primarily from
human and animal fecal waste due to inadequate sewage treatment. In many
underdeveloped countries, sewage is discharged into local waters either
untreated or after only rudimentary treatment. In developed countries
untreated sewage discharge can occur from overflows of combined sewer
systems, poorly managed livestock factory farms, and leaky or broken
sewage collection systems (see Figure Overflowing Sanitary Sewer).
Water with pathogens can be remediated by adding chlorine or ozone, by
boiling, or by treating the sewage in the first place.
Overflowing Sanitary Sewer A manhole cover blown
off by a June 2006 sanitary sewer overflow in Rhode
Island. Source: U.S. Environmental Protection Agency
via Wikimedia Commons
Oil spills are another kind of organic pollution. Oil spills can result from
supertanker accidents such as the Exxon Valdez in 1989, which spilled 10
million gallons of oil into the rich ecosystem of offshore south Alaska and
killed massive numbers of animals. The largest marine oil spill was the
Deepwater Horizon disaster, which began with a natural gas explosion (see
Figure Deepwater Horizon Explosion) at an oil well 65 km offshore of
Louisiana and flowed for 3 months in 2010, releasing an estimated 200
million gallons of oil. The worst oil spill ever occurred during the Persian
Gulf war of 1991, when Iraq deliberately dumped approximately 200
million gallons of oil in offshore Kuwait and set more than 700 oil well
fires that released enormous clouds of smoke and acid rain for over nine
months. During an oil spill on water, oil floats to the surface because it is
less dense than water, and the lightest hydrocarbons evaporate, decreasing
the size of the spill but polluting the air. Then, bacteria begin to decompose
the remaining oil, in a process that can take many years. After several
months only about 15% of the original volume may remain, but it is in thick
asphalt lumps, a form that is particularly harmful to birds, fish, and
shellfish. Cleanup operations can include skimmer ships that vacuum oil
from the water surface (effective only for small spills), controlled burning
(works only in early stages before the light, ignitable part evaporates but
also pollutes the air), dispersants (detergents that break up oil to accelerate
its decomposition, but some dispersants may be toxic to the ecosystem), and
bioremediation (adding microorganisms that specialize in quickly
decomposing oil, but this can disrupt the natural ecosystem).
Deepwater Horizon Explosion Boats fighting the fire from an
explosion at the Deepwater Horizon drilling mee in ce oF Mexico
offshore Louisiana on nee 20, 2010. Source:
( 1 via Wikimedia Canons
xic chemicals involve many different kinds and sources, primarily from
acne ore maining. General kinds of toxic chemicals include hazardous
chemicals, which are a wide variety of synthetic organic and inorganic
oe such as al bases, cyanide, and a class of compounds called
ersistent organi ollutants that includes DDT (pesticide), dioxin
(herbicide by- oa and PCBs (polychlorinated biphenyls, which were
used as a liquid insulator in electric transformers). Persistent organic
pollutants are long-lived in the environment, accumulate through the food
chain (bioaccumulation), and can be toxic. Another category of toxic
chemicals includes radioactive materials such as cesium, iodine, uranium,
and radon gas, which can result in long-term exposure to radioactivity if it
gets into the body. A final group of toxic chemicals is heavy metals such as
lead, mercury, arsenic, cadmium, and chromium, which can accumulate
through the food chain. Heavy metals are commonly produced by industry
and at metallic ore mines. Arsenic and mercury are discussed in more detail
below. The US EPA regulates 83 contaminants in drinking water to ensure a
safe public water supply. Similarly, at the international level the World
Health Organization has drinking water standards for a variety of
contaminants.
Arsenic (As) has been famous as an agent of death for many centuries. In
large doses arsenic causes cancer and can be fatal. Only recently have
scientists recognized that health problems can be caused by drinking small
arsenic concentrations in water over a long time. It attacks the central
nervous system and can damage the respiratory system, bladder, lungs,
liver, and kidneys. It enters the water supply naturally from weathering of
As-rich minerals and from human activities such as coal burning and
smelting of metallic ores. The worst case of arsenic poisoning occurred in
the densely populated impoverished country of Bangladesh, which had
experienced 100,000s of deaths from diarrhea and cholera each year from
drinking surface water contaminated with pathogens due to improper
sewage treatment. In the 1970s the United Nations provided aid for millions
of shallow water wells, which resulted in a dramatic drop in pathogenic
diseases. Unfortunately, many of the wells produced water naturally rich in
arsenic. Tragically, there are an estimated 77 million people (about half of
the population) who inadvertently may have been exposed to toxic levels of
arsenic in Bangladesh as a result. The World Health Organization has called
it the largest mass poisoning of a population in history.
Mercury (Hg) is used in a variety of electrical products, such as dry cell
batteries, fluorescent light bulbs, and switches, as well as in the
manufacture of paint, paper, vinyl chloride, and fungicides. In the
methylmercury form (CH3Hg’) it is highly toxic; > 1 ppb of methylmercury
represents water contaminated with mercury. Mercury concentrates in the
food chain, especially in fish, in a process caused biomagnification (see
Sidebar Biomagnification). It acts on the central nervous system and can
cause loss of sight, feeling, and hearing as well as nervousness, shakiness,
and death. Like arsenic, mercury enters the water supply naturally from
weathering of Hg-rich minerals and from human activities such as coal
burning and metal processing. A famous mercury poisoning case in
Minamata, Japan involved methylmercury-rich industrial discharge that
caused high Hg levels in fish. People in the local fishing villages ate fish up
to three times per day for over 30 years, which resulted in over 2,000
deaths. During that time the responsible company and national government
did little to mitigate, help alleviate, or even acknowledge the problem.
Note:
Biomagnification
Biomagnification represents the processes in an ecosystem that cause
greater concentrations of a chemical, such as methylmercury, in organisms
higher up the food chain. Mercury and methylmercury are present in only
very small concentrations in seawater; however, at the base of the food
chain algae absorb methylmercury. Then, small fish eat the algae, large fish
and other organisms higher in the food chain eat the small fish, and so on.
Fish and other aquatic organisms absorb methylmercury rapidly but
eliminate it slowly from the body. Therefore, each step up the food chain
increases the concentration from the step below (see Figure
Biomagnification). Largemouth bass can concentrate methylmercury up to
10 million times over the water concentration and fish-eating birds can
concentrate it even higher. Other chemicals that exhibit biomagnification
are DDT, PCBs, and arsenic.
Biomagnificatio
n An illustrative
example of
biomagnification
of mercury from
water through the
food chain and
into a bird's egg.
Source: U.S.
Geological
Survey
Other water pollutants include sediment and heat. Muddy water is bad for
drinking but even worse for underwater plants that need sunlight for
photosynthesis. Much of the sediment in water bodies is derived from the
erosion of soil, so it also represents a loss of agricultural productivity.
Thermal pollution involves the release of heated waters from power plants
and industry to surface water, causing a drop in the dissolved O> content,
which can stress fish.
Hard water contains abundant calcium and magnesium, which reduces its
ability to develop soapsuds and enhances scale (calcium and magnesium
carbonate minerals) formation on hot water equipment. Water softeners
remove calcium and magnesium, which allows the water to lather easily
and resist scale formation. Hard water develops naturally from the
dissolution of calcium and magnesium carbonate minerals in soil; it does
not have negative health effects in people.
Groundwater pollution can occur from underground sources and all of the
pollution sources that contaminate surface waters. Common sources of
groundwater pollution are leaking underground storage tanks for fuel, septic
tanks, agricultural activity, and landfills. Common groundwater pollutants
include nitrate, pesticides, volatile organic compounds, and petroleum
products. Polluted groundwater can be a more serious problem than
polluted surface water because the pollution in groundwater may go
undetected for a long time because usually it moves very slowly. As a
result, the pollution in groundwater may create a contaminant plume, a
large body of flowing polluted groundwater (see Figure Contaminant
Plume in Groundwater), making cleanup very costly. By the time
groundwater contamination is detected, the entity responsible for the
pollution may be bankrupt or nonexistent. Another troublesome feature of
groundwater pollution is that small amounts of certain pollutants, e.g.,
petroleum products and organic solvents, can contaminate large areas. In
Denver, Colorado 80 liters of several organic solvents contaminated 4.5
trillion liters of groundwater and produced a 5 km long contaminant plume.
Most groundwater contamination occurs in shallow, unconfined aquifers
located near the contamination source. Confined aquifers are less
susceptible to pollution from the surface because of protection by the
confining layer. A major threat to groundwater quality is from
underground fuel storage tanks. Fuel tanks commonly are stored
underground at gas stations to reduce explosion hazards. Before 1988 in the
U.S. these storage tanks could be made of metal, which can corrode, leak,
and quickly contaminate local groundwater. Now, leak detectors are
required and the metal storage tanks are supposed to be protected from
corrosion or replaced with fiberglass tanks. Currently there are around
600,000 underground fuel storage tanks in the U.S. and over 30% still do
not comply with EPA regulations regarding either release prevention or leak
detection.
Contaminant Plume in Groundwater Mapping how a contaminant
plume will migrate once it reaches groundwater requires understanding
of the pollutant's chemical properties, local soil characteristics, and
how permeable the aquifer is. Source: United States Geological Survey
Sustainable Solutions to the Water Pollution Crisis?
Resolution of the global water pollution crisis described at the beginning of
this section requires multiple approaches to improve the quality of our fresh
water and move towards sustainability. The most deadly form of water
pollution, pathogenic microorganisms that cause waterborne diseases, kills
almost 2 million people in underdeveloped countries every year. The best
strategy for addressing this problem is proper sewage (wastewater)
treatment. Untreated sewage is not only a major cause of pathogenic
diseases, but also a major source of other pollutants, including oxygen-
demanding waste, plant nutrients (N and P), and toxic heavy metals.
Wastewater treatment is done at a sewage treatment plant in urban areas
and through a septic tank system in rural areas.
The main purpose of a sewage treatment plant is to remove organic matter
(oxygen-demanding waste) and kill bacteria; special methods also can be
used to remove plant nutrients and other pollutants. The numerous
processing steps at a conventional sewage treatment plant (see Figure Steps
at a Sewage Treatment Plant) include pretreatment (screening and
removal of sand and gravel), primary treatment (settling or floatation to
remove organic solids, fat, and grease), secondary treatment (aerobic
bacterial decomposition of organic solids), tertiary treatment (bacterial
decomposition of nutrients and filtration), disinfection (treatment with
chlorine, ozone, ultraviolet light, or bleach), and either discharge to surface
waters (usually a local river) or reuse for some other purpose, such as
irrigation, habitat preservation, and artificial groundwater recharge. The
concentrated organic solid produced during primary and
secondarytreatment is called sludge, which is treated in a variety of ways
including landfill disposal, incineration, use as fertilizer, and anaerobic
bacterial decomposition, which is done in the absence of oxygen. Anaerobic
decomposition of sludge produces methane gas, which can be used as an
energy source. To reduce water pollution problems, separate sewer systems
(where street runoff goes to rivers and only wastewater goes to a
wastewater treatment plant) are much better than combined sewer systems,
which can overflow and release untreated sewage into surface waters during
heavy rain. Some cities such as Chicago, Illinois have constructed large
underground caverns and also use abandoned rock quarries to hold storm
sewer overflow. After the rain stops, the stored water goes to the sewage
treatment plant for processing.
Bk
es Cl, eee =|
;
2228 —
'
A
Steps at a Sewage Treatment Plant The numerous processing steps
at a conventional sewage treatment plant include pretreatment
(screening and removal of sand and gravel), primary treatment
(settling or floatation to remove organic solids, fat, and grease),
secondary treatment (aerobic bacterial decomposition of organic
solids), tertiary treatment (bacterial decomposition of nutrients and
filtration), disinfection (treatment with chlorine, ozone, ultraviolet
light, or bleach), and either discharge to surface waters (usually a local
river) or reuse for some other purpose, such as irrigation, habitat
preservation, and artificial groundwater recharge. Source: Leonard
G.via Wikipedia
A septic tank system is an individual sewage treatment system for homes in
rural and even some urban settings. The basic components of a septic tank
system (see Figure Septic System) include a sewer line from the house, a
septic tank (a large container where sludge settles to the bottom and
microorganisms decompose the organic solids anaerobically), and the drain
field (network of perforated pipes where the clarified water seeps into the
soil and is further purified by bacteria). Water pollution problems occur if
the septic tank malfunctions, which usually occurs when a system is
established in the wrong type of soil or maintained poorly.
SI udge a Effluent
Sewage enters To drain field
from home and laterals
Septic System Septic tank system for
sewage treatment. Source: United
States Geological Survey
For many developing countries, financial aid is necessary to build adequate
sewage treatment facilities; however, the World Health Organization
estimates an estimated cost savings of between $3 and $34 for every $1
invested in clean water delivery and sanitation (Water for Life, 2005). The
cost savings are from health care savings, gains in work and school
productivity, and deaths prevented. Simple and inexpensive techniques for
treating water at home include chlorination, filters, and solar disinfection.
Another alternative is to use constructed wetlands technology (marshes
built to treat contaminated water), which is simpler and cheaper than a
conventional sewage treatment plant.
Bottled water is not a sustainable solution to the water crisis, despite
exponential growth in popularity in the U.S. and the world. Bottled water is
not necessarily any safer than the U.S. public water supply, it costs on
average about 700 times more than U.S. tap water, and every year it uses
approximately 200 billion plastic and glass bottles that have a relatively low
rate of recycling. Compared to tap water, it uses much more energy, mainly
in bottle manufacturing and long-distance transportation. If you don’t like
the taste of your tap water, then please use a water filter instead of bottled
water!
Storm Drain Curbside storm drain receiving urban runoff. Source: By
Robert Lawton via Wikimedia Commons
Additional sustainable solutions to the water pollution crisis include
legislation to eliminate or greatly reduce point sources of water pollution. In
the U.S., the Clean Water Act of 1972 and later amendments led to major
improvements in water quality (see Sidebar Clean Water Act). Nonpoint
sources of water pollution, e.g., agricultural runoff and urban runoff (see
Figure Storm Drain), are much harder to regulate because of their
widespread, diffuse nature. There are many construction and agricultural
practices that reduce polluted runoff including no-till farming and sediment
traps. Artificial aeration or mechanical mixing can remediate lakes with
oxygen depletion. Specific things that we can do to reduce urban runoff
include the following: keep soil, leaves, and grass clippings off driveways,
sidewalks, and streets; don't pour used motor oil, antifreeze, paints,
pesticides, or any household hazardous chemical down the storm sewer or
drain; recycle used motor oil; use hazardous waste disposal programs
offered by the community; compost your organic waste; don't use fertilizers
and herbicides on your lawn; and flush pet waste down the toilet.
Note:
Clean Water Act
During the early 1900s rapid industrialization in the U.S. resulted in
widespread water pollution due to free discharge of waste into surface
waters. The Cuyahoga River in northeast Ohio caught fire numerous times
(see Figure Cuyahoga River on Fire), including a famous fire in 1969 that
caught the nation’s attention. In 1972 Congress passed one of the most
important environmental laws in U.S. history, the Federal Water Pollution
Control Act, which is more commonly called the Clean Water Act. The
purpose of the Clean Water Act and later amendments is to maintain and
restore water quality, or in simpler terms to make our water swimmable
and fishable. It became illegal to dump pollution into surface water unless
there was formal permission and U.S. water quality improved significantly
as a result. More progress is needed because currently the EPA considers
over 40,000 U.S. water bodies as impaired, most commonly due to
pathogens, metals, plant nutrients, and oxygen depletion. Another concern
is protecting groundwater quality, which is not yet addressed sufficiently
by federal law.
Cuyahoga River on Fire Source: National Oceanic and
Atmospheric
Sometimes slow flow through a soil can naturally purify groundwater
because some pollutants, such as P, pesticides, and heavy metals,
chemically bind with surfaces of soil clays and iron oxides. Other pollutants
are not retained by soil particles: These include N, road salt, gasoline fuel,
the herbicide atrazine, tetrachloroethylene (a carcinogenic cleaning solvent
used in dry cleaning), and vinyl chloride. In other cases, slow groundwater
flow can allow bacteria to decompose dead organic matter and certain
pesticides. There are many other ways to remediate polluted groundwater.
Sometimes the best solution is to stop the pollution source and allow natural
cleanup. Specific treatment methods depend on the geology, hydrology, and
pollutant because some light contaminants flow on top of groundwater,
others dissolve and flow with groundwater, and dense contaminants can
sink below groundwater. A common cleanup method called pump and treat
involves pumping out the contaminated groundwater and treating it by
oxidation, filtration, or biological methods. Sometimes soil must be
excavated and sent to a landfill. In-situ treatment methods include adding
chemicals to immobilize heavy metals, creating a permeable reaction zone
with metallic iron that can destroy organic solvents, or using
bioremediation by adding oxygen or nutrients to stimulate growth of
microorganisms.
Review Questions
Exercise:
Problem:
What are the major kinds of water pollutants and how do they degrade
water quality?
Exercise:
Problem:
How would you rank the water pollution problems described in this
chapter? Why?
Exercise:
Problem:
Why is untreated sewage such an important water pollutant to
remediate?
Exercise:
Problem:
What should society learn from the case history of Love Canal?
Exercise:
Problem:
Why are people facing a crisis involving water pollution and how can
we solve it?
References
Water for Life: Making it Happen (2005) World Health Organization and
UNICEF. Retrieved from
http://www.who.int/water_ sanitation health/waterforlife.pdf
World Health Statistics (2010) World Health Organization. Retrieved from
http://www.who.int/whosis/whostat/EN_ WHS10 Full. pdf
Glossary
arsenic
A type of water pollutant that can be fatal in large doses and can cause
health problems in small doses over a long time.
biochemical oxygen demand
The amount of oxygen used by aerobic (in presence of oxygen)
bacterial decomposition of organic matter.
bioremediation
Method of groundwater remediation involving the addition oxygen or
nutrients. to stimulate growth of microorganisms, which decompose an
organic pollutant.
bottled water
Drinking water packaged in plastic bottles or glass bottles, bottled
water is not a sustainable solution to the water crisis because of the
nonrenewable energy and material resources involved in
manufacturing and transporting it.
combined sewer systems
A single set of underground pipes used to collect both sewage and.
storm water runoff from streets for wastewater treatment.
constructed wetland
Marsh built to treat contaminated water.
contaminant plume
A large body of flowing polluted groundwater.
cultural eutrophication
Rapid aquatic plant growth, particularly algae, in a surface water body.
excessive plant nutrient
A type of water pollutant involving a limiting plant nutrient that
usually is present in water at low concentrations and therefore restricts
the total amount of plant growth, examples include nitrogen and
phosphorous.
hard water
Water with abundant calcium and magnesium, which reduces its ability
to develop soapsuds and enhances scale; hard water does not have
negative health effects in people.
heat
A type of water pollutant that causes a drop in the dissolved oxygen
content, which can stress fish.
heavy metal
A type of water pollutant involving elements such as lead, mercury,
arsenic, cadmium, and chromium, which can accumulate through the
food chain.
hypoxia
Very low oxygen water due to prolific growth of algae, algal death,
and then decomposition, also called dead zone.
mercury
A type of water pollutant that acts on the central nervous system and
can cause loss of sight, feeling, and hearing as well as nervousness,
Shakiness, and death.
nonpoint source (of water pollution)
Large and diffuse location where a pollution source occurs.
oil spill
A type of organic water pollutant involving the release of liquid
petroleum into the environment due to human activity.
oxygen-demanding waste
A type of water pollutant involving abundant dead organic matter.
pathogens
Disease-causing microorganisms, e.g., viruses, bacteria, parasitic
worms, and protozoa, which cause a variety of intestinal diseases such
as dysentery, typhoid fever, hepatitis, and cholera.
persistent organic pollutant
A group of organic water pollutants that are long-lived in the
environment, accumulate through the food chain, and can be toxic.
point source (of water pollution)
Readily identifiable and relatively small location where a pollution
source occurs.
sediment
A type of water pollutant that degrades drinking water and can kill
underwater plants that need sunlight for photosynthesis.
septic tank system
An individual sewage treatment system for homes in rural and even
some urban settings.
sewage treatment plant
A facility that processes wastewater with the main goal of removing
organic matter (oxygen-demanding waste) and killing bacteria.
sludge
Concentrated organic solid produced during primary and
secondarytreatment of sewage treatment.
solvent
Capacity of a liquid such as water to dissolve soluble minerals.
total dissolved solids
Total amount of dissolved material in water, typically reported in parts
per million (ppm) units.
toxic chemical
A type of organic water pollutant involving chemicals with a severe
human health risk.
underground fuel storage tank
A type of water pollutant if it leaks.
water pollution
Contamination of water by an excess amount of a substance that can
cause harm to human beings and the ecosystem.
Case Study: The Love Canal Disaster
In this module, The Love Canal Disaster is described.
One of the most famous and important examples of groundwater pollution
in the U.S. is the Love Canal tragedy in Niagara Falls, New York. It is
important because the pollution disaster at Love Canal, along with similar
pollution calamities at that time (Times Beach, Missouri and Valley of
Drums, Kentucky), helped to create Superfund, a federal program
instituted in 1980 and designed to identify and clean up the worst of the
hazardous chemical waste sites in the U.S.
Love Canal is a neighborhood in Niagara Falls named after a large ditch
(approximately 15 m wide, 3—12 m deep, and 1600 m long) that was dug in
the 1890s for hydroelectric power. The ditch was abandoned before it
actually generated any power and went mostly unused for decades, except
for swimming by local residents. In the 1920s Niagara Falls began dumping
urban waste into Love Canal, and in the 1940s the U.S. Army dumped
waste from World War II there, including waste from the frantic effort to
build a nuclear bomb. Hooker Chemical purchased the land in 1942 and
lined it with clay. Then, the company put into Love Canal an estimated
21,000 tons of hazardous chemical waste, including the carcinogens
benzene, dioxin, and PCBs in large metal barrels and covered them with
more clay. In 1953, Hooker sold the land to the Niagara Falls school board
for $1, and included a clause in the sales contract that both described the
land use (filled with chemical waste) and absolved them from any future
damage claims from the buried waste. The school board promptly built a
public school on the site and sold the surrounding land for a housing project
that built 200 or so homes along the canal banks and another 1,000 in the
neighborhood (see Figure Love Canal). During construction, the canal’s
clay cap and walls were breached, damaging some of the metal barrels.
Love Canal Source: US Environmental
Protection Agency
Eventually, the chemical waste seeped into people's basements, and the
metal barrels worked their way to the surface. Trees and gardens began to
die; bicycle tires and the rubber soles of children's shoes disintegrated in
noxious puddles. From the 1950s to the late 1970s, residents repeatedly
complained of strange odors and substances that surfaced in their yards.
City officials investigated the area, but did not act to solve the problem.
Local residents allegedly experienced major health problems including high
rates of miscarriages, birth defects, and chromosome damage, but studies by
the New York State Health Department disputed that. Finally, in 1978
President Carter declared a state of emergency at Love Canal, making it the
first human-caused environmental problem to be designated that way. The
Love Canal incident became a symbol of improperly stored chemical waste.
Clean up of Love Canal, which was funded by Superfund and completely
finished in 2004, involved removing contaminated soil, installing drainage
pipes to capture contaminated groundwater for treatment, and covering it
with clay and plastic. In 1995, Occidental Chemical (the modern name for
Hooker Chemical) paid $102 million to Superfund for cleanup and $27
million to Federal Emergency Management Association for the relocation
of more than 1,000 families. New York State paid $98 million to EPA and
the US government paid $8 million for pollution by the Army. The total
clean up cost was estimated to be $275 million. The only good thing about
the Love Canal tragedy is that it helped to create Superfund, which has
analyzed tens of thousands of hazardous waste sites in the U.S. and cleaned
up hundreds of the worst ones. Nevertheless, over 1,000 major hazardous
waste sites with a significant risk to human health or the environment are
still in the process of being cleaned.
Glossary
superfund
A federal program created in 1980 and designed to identify and clean
up the worst of the hazardous chemical waste sites in the U.S.
Mineral Resources: Formation, Mining, Environmental Impact
In this module, the following topics will be covered: 1) the importance of minerals to
society; 2) the factors that control availability of mineral resources, 3) the future world
mineral supply and demand; 4) the environmental impact of mining and processing of
minerals; 5) solutions to the crisis involving mineral supply
Learning Objectives
After reading this module, students should be able to
¢ know the importance of minerals to society
¢ know factors that control availability of mineral resources
¢ know why future world mineral supply and demand is an important issue
¢ understand the environmental impact of mining and processing of minerals
e understand how we can work toward solving the crisis involving mineral supply
Importance of Minerals
Mineral resources are essential to our modern industrial society and they are used
everywhere. For example, at breakfast you drink some juice in a glass (made from
melted quartz sand), eat from a ceramic plate (created from clay minerals heated at
high temperatures), sprinkle salt (halite) on your eggs, use steel utensils (from iron ore
and other minerals), read a magazine (coated with up to 50% kaolinite clay to give the
glossy look), and answer your cellphone (containing over 40 different minerals
including copper, silver, gold, and platinum). We need minerals to make cars,
computers, appliances, concrete roads, houses, tractors, fertilizer, electrical
transmission lines, and jewelry. Without mineral resources, industry would collapse
and living standards would plummet. In 2010, the average person in the U.S.
consumed more than16,000 pounds of mineral resources[footnote] (see Table Per
Capita Consumption of Minerals). With an average life expectancy of 78 years, that
translates to about1.3 million pounds of mineral resources over such a person’s
lifetime. Here are a few statistics that help to explain these large values of mineral use:
an average American house contains about 250,000 pounds of minerals (see Figure
Mineral Use in the Kitchen for examples of mineral use in the kitchen), one mile of
Interstate highway uses 170 million pounds of earth materials, and the U.S. has nearly
4 million miles of roads. All of these mineral resources are nonrenewable, because
nature usually takes hundreds of thousands to millions of years to produce mineral
deposits. Early hominids used rocks as simple tools as early as 2.6 million years ago.
At least 500,000 years ago prehistoric people used flint (fine-grained quartz) for
knives and arrowheads. Other important early uses of minerals include mineral
pigments such as manganese oxides and iron oxides for art, salt for food preservation,
stone for pyramids, and metals such as bronze (typically tin and copper), which is
stronger than pure copper and iron for steel, which is stronger than bronze.
Americans also consumed more than 21,000 pounds of energy resources from the
Earth including coal, oil, natural gas, and uranium.
1. RADIO: Includes aluminum, copper, gold, iron,
and petroleum products.
2. TOASTER: Includes copper, iron, nickel, mica,
chromium, and petroleum products.
3. ELECTRICAL WIRING: Includes copper, aluminum,
and petroleum products.
4, MICROWAVE: Includes copper, gold, iron, nickel,
and silica.
5. STOVE: Includes aluminum, copper, iron, nickel,
and silica.
6, REFRIGERATOR: Includes aluminum, copper, iron,
nickel, petroleum products, and zinc.
7. TABLE SALT: Includes halite; light salt can be made
from sylvite. Most salt has added iodine.
8. PLATES: Includes clays, silica, and feldspar.
9. CUTLERY: Includes iron. nickel, silver, and chromium.
10, CLOCK: Includes iron, nickel, petroleum products,
and silica.
11. STAINLESS STEEL SINK: Includes iron and nickcl.
12. BLACKBOARD: Includes clays. Chalk includes
limestone or petrolcum products.
13. MAGNET: Includes cobalt.
l4. DISH RACK: Made of petroleum products.
Mineral Use in the Kitchen Source: U.S. Geological Survey
Per Capita Consumption
Mineral of Minerals — 2010
(Pounds per Person)
Bauxite
(Aluminum) o
Cement 496
Clays 164
Copper 12
Per Capita Consumption of
Minerals - Lifetime
(Pounds Per Person)
5,090
38,837
12,841
939.6
Iron Ore 357 27,953
Lead 11 861
Manganese fs) 392
as 217 16,991
Potash 37 2,897
Salt 421 32,964
Sand,
Gravel, 14,108 1,104,656
Stone
Soda Ash 36 2,819
Sulfur 86 6,734
Zinc 6 470
ae 24 1,879
NoaaeE - ss
Total 16,377 1,282,319
Per capita consumption of nonenergy related minerals and metals in the U.S. for 2010
and for a lifetime of 78.3 years assuming 2010 mineral consumption rates Sources: US
Geological Survey, National Mining Association, and U.S. Census Bureau
Mineral Resource Principles
A geologist defines a mineral as a naturally occurring inorganic solid with a defined
chemical composition and crystal structure (regular arrangement of atoms). Minerals
are the ingredients of rock, which is a solid coherent (i.e., will not fall apart) piece of
planet Earth. There are three classes of rock, igneous, sedimentary, and metamorphic.
Igneous rocks form by cooling and solidification of hot molten rock called lava or
magma. Lava solidifies at the surface after it is ejected by a volcano, and magma cools
underground. Sedimentary rocks form by hardening of layers of sediment (loose
grains such as sand or mud) deposited at Earth's surface or by mineral precipitation,
i.e., formation of minerals in water from dissolved mineral matter. Metamorphic
rocks form when the shape or type of minerals in a preexisting rock changes due to
intense heat and pressure deep within the Earth. Ore is rock with an enrichment of
minerals that can be mined for profit. Sometimes ore deposits (locations with
abundant ore) can be beautiful, such as the giant gypsum crystals at the amazing Cave
of the Crystals in Mexico (see Figure Giant Gypsum Crystals). The enrichment
factor, which is the ratio of the metal concentration needed for an economic ore
deposit over the average abundance of that metal in Earth’s crust, is listed for several
important metals in the Table Enrichment Factor. Mining of some metals, such as
aluminum and iron, is profitable at relatively small concentration factors, whereas for
others, such as lead and mercury, it is profitable only at very large concentration
factors. The metal concentration in ore (column 3 in Table Enrichment Factor) can
also be expressed in terms of the proportion of metal and waste rock produced after
processing one metric ton (1,000 kg) of ore. Iron is at one extreme, with up to 690 kg
of Fe metal and only 310 kg of waste rock produced from pure iron ore, and gold is at
the other extreme with only one gram (.03 troy oz) of Au metal and 999.999 kg of
waste rock produced from gold ore.
Giant Gypsum Crystals Giant gypsum crystals in the
Cave of Crystals in Naica, Mexico. There are crystals
up to 11 m long in this cave, which is located about 1
km underground. Source: National Geographic via
Wikipedia
Metal Average Concentration Needed Approximate
Concentration for Economic Mine Enrichment
in Crust (%) (%) Factor
Aluminum 8 35 4
Iron 5 20 - 69 4-14
Copper 0.005 0.4 - 0.8 80 - 160
0.0001[footnote]
Economic concentration
Gold 0.0000004 value for gold comes 250
from Craig, Vaughan,
Skinner (2011).
Lead 0.0015 4 2,500
Mercury 0.00001 0.1 10,500
Enrichment FactorApproximate enrichment factors of selected metals needed before
profitable mining is possible. Source: US Geological Survey Professional Paper 820,
1973
Formation of Ore Deposits
Ore deposits form when minerals are concentrated—sometimes by a factor of many
thousands—in rock, usually by one of six major processes. These include the
following: (a) igneous crystallization, where molten rock cools to form igneous rock.
This process forms building stone such as granite, a variety of gemstones, sulfur ore,
and metallic ores, which involve dense chromium or platinum minerals that sink to the
bottom of liquid magma. Diamonds form in rare Mg-rich igneous rock called
kimberlite that originates as molten rock at 150—200 km depth (where the diamonds
form) and later moves very quickly to the surface, where it erupts explosively. The
cooled magma forms a narrow, carrot-shaped feature called a pipe. Diamond mines in
kimberlite pipes can be relatively narrow but deep (see Figure A Diamond Mine). (b)
Hydrothermal is the most common ore-forming process. It involves hot, salty water
that dissolves metallic elements from a large area and then precipitates ore minerals in
a smaller area, commonly along rock fractures and faults. Molten rock commonly
provides the heat and the water is from groundwater, the ocean, or the magma itself.
The ore minerals usually contain sulfide (S*) bonded to metals such as copper, lead,
zinc, mercury, and silver. Actively forming hydrothermal ore deposits occur at
undersea mountain ranges, called oceanic ridges, where new ocean crust is produced.
Here, mineral-rich waters up to 350°C sometimes discharge from cracks in the crust
and precipitate a variety of metallic sulfide minerals that make the water appear black;
they are called black smokers (see Figure Black Smokers). (c) Metamorphism
occurs deep in the earth under very high temperature and pressure and produces
several building stones, including marble and slate, as well as some nonmetallic ore,
including asbestos, talc, and graphite. (d) Sedimentary processes occur in rivers that
concentrate sand and gravel (used in construction), as well as dense gold particles and
diamonds that weathered away from bedrock. These gold and diamond ore bodies are
called placer deposits. Other sedimentary ore deposits include the deep ocean floor,
which contains manganese and cobalt ore deposits and evaporated lakes or seawater,
which produce halite and a variety of other salts. (e) Biological processes involve the
action of living organisms and are responsible for the formation of pearls in oysters, as
well as phosphorous ore in the feces of birds and the bones and teeth of fish. (f)
Weathering in tropical rain forest environments involves soil water that concentrates
insoluble elements such as aluminum (bauxite) by dissolving away the soluble
elements.
A Diamond Mine Udachnaya Pipe, an open-pit diamond mine in Russia,
is more than 600 meters (1,970 ft) deep, making it the third deepest open-
pit mine in the world. Source: Stapanov Alexander via Wikimedia
Commons
Black Smoker A billowing discharge
of superheated mineral-rich water at an
oceanic ridge, in the Atlantic Ocean.
Black “smoke” is actually from
metallic sulfide minerals that form
modern ore deposits. Source: P. Rona
of U.S. National Oceanic and
Atmospheric Administration via
Wikimedia Commons
Mining and Processing Ore
There are two kinds of mineral mines, surface mines and underground mines. The
kind of mine used depends on the quality of the ore, i.e., concentration of mineral and
its distance from the surface. Surface mines include open-pit mines, which commonly
involve large holes that extract relatively low-grade metallic ore (see Figure Open Pit
Mine), strip mines, which extract horizontal layers of ore or rock, and placer mines,
where gold or diamonds are extracted from river and beach sediment by scooping up
(dredging) the sediment and then separating the ore by density. Large, open-pit mines
can create huge piles of rock (called overburden) that was removed to expose the ore
as well as huge piles of ore for processing. Underground mines, which are used when
relatively high-grade ore is too deep for surface mining, involve a network of tunnels
to access and extract the ore. Processing metallic ore (e.g., gold, silver, iron, copper,
zinc, nickel, and lead) can involve numerous steps including crushing, grinding with
water, physically separating the ore minerals from non-ore minerals often by density,
and chemically separating the metal from the ore minerals using methods such as
smelting (heating the ore minerals with different chemicals to extract the metal) and
leaching (using chemicals to dissolve the metal from a large volume of crushed rock).
The fine-grained waste produced from processing ore is called tailings. Slag is the
glassy unwanted by-product of smelting ore. Many of the nonmetallic minerals and
rocks do not require chemical separation techniques.
Open Pit Mine Bingham Canyon copper mine in Utah, USA. At 4 km
wide and 1.2 km deep, it is the world’s deepest open-pit mine. It began
operations in 1906. Source: Tim Jarrett via Wikimedia Commons
Mineral Resources and Sustainability Issues
Our heavy dependence on mineral resources presents humanity with some difficult
challenges related to sustainability, including how to cope with finite supplies and how
to mitigate the enormous environmental impacts of mining and processing ore. As
global population growth continues—and perhaps more importantly, as standards of
living rise around the world—demand for products made from minerals will increase.
In particular, the economies of China, India, Brazil, and a few other countries are
growing very quickly, and their demand for critical mineral resources also is
accelerating. That means we are depleting our known mineral deposits at an increasing
rate, requiring that new deposits be found and put into production. Figure Demand for
Nonfuel Minerals Materials shows the large increase in US mineral consumption
between 1900 and 2006. Considering that mineral resources are nonrenewable, it is
reasonable to ask how long they will last. The Table Strategic Minerals gives a
greatly approximated answer to that question for a variety of important and strategic
minerals based on the current production and the estimated mineral reserves. Based
on this simplified analysis, the estimated life of these important mineral reserves
varies from more than 800 to 20 years. It is important to realize that we will not
completely run out of any of these minerals but rather the economically viable mineral
deposits will be used up. Additional complications arise if only a few countries
produce the mineral and they decide not to export it. This situation is looming for rare
earth elements, which currently are produced mainly by China, which is threatening to
limit exports of these strategic minerals.
Demand for Nonfuel Minerals Materials US mineral
consumption from 1900 - 2006, excluding energy-related
minerals Source: U.S. Geological Survey
Mineral Uses 2010 2010 Estimated
Production Reserves Life of
Rare earths
Lithium
Phosphate
rock
Platinum
Group
Aluminum
ore
Titanium
minerals
Cobalt
catalysts,
alloys,
electronics,
phosphors,
magnets
ceramics,
glass,
lithium-ion
batteries in
electronics
and electric
cars
fertilizer,
animal feed
supplement
catalysts,
electronics,
glass, jewelry
Al cans,
airplanes,
building,
electrical
white
pigment,
metal in
airplanes and
human joint
replacements
airplane
engines,
metals,
chemicals
(thousands
of metric
tons)
130
25.3
176,000
0.4
211,000
6,300
88
(thousands
of metric
tons)
110,000
13,000
65,000,000
66
28,000,000
690,000
7,300
Reserves
(years)
846
914
369
178
133
110
83
Iron ore
Nickel
Manganese
Copper
Silver
Zinc
Lead
Tin
Gold
main
ingredient in
steel
important
alloy in steel,
electroplating
important
alloy in steel
electrical
wire,
electronics,
pipes,
ingredient in
brass
industry,
coins,
jewelry,
photography
galvanized
steel, alloys,
brass
batteries
electrical,
cans,
construction,
jewelry, arts,
electronics,
dental
2,400,000
1,550
13,000
16,200
22:2
12,000
4,100
261
2.5
180,000,000
76,000
630,000
630,000
510
250,000
80,000
5,200
ol
49
48
39
23
2
20
20
20
Strategic MineralsUses, world production in 2010, and estimated projected lifetime of
reserves (ore that is profitable to mine under current conditions) for selected minerals
Source: US Geological Survey Mineral Commodity Summaries, 2011
A more complex analysis of future depletions of our mineral supplies predicts that 20
out of 23 minerals studied will likely experience a permanent shortfall in global supply
by 2030 where global production is less than global demand (Clugston, 2010).
Specifically this study concludes the following: for cadmium, gold, mercury,
tellurium, and tungsten—they have already passed their global production peak, their
future production only will decline, and it is nearly certain that there will be a
permanent global supply shortfall by 2030; for cobalt, lead, molybdenum, platinum
group metals, phosphate rock, silver, titanium, and zinc—they are likely at or near
their global production peak and there is a very high probability that there will be a
permanent global supply shortfall by 2030; for chromium, copper, indium, iron ore,
lithium, magnesium compounds, nickel, and phosphate rock—they are expected to
reach their global production peak between 2010 and 2030 and there is a high
probability that there will be a permanent global supply shortfall by 2030; and for
bauxite, rare earth minerals, and tin—they are not expected to reach their global
production peak before 2030 and there is a low probability that there will be a
permanent global supply shortfall by 2030. It is important to note that these kinds of
predictions of future mineral shortages are difficult and controversial. Other scientists
disagree with Clugston’s predictions of mineral shortages in the near future.
Predictions similar to Clugston were made in the 1970s and they were wrong. It is
difficult to know exactly the future demand for minerals and the size of future mineral
reserves. The remaining life for specific minerals will decrease if future demand
increases. On the other hand, mineral reserves can increase if new mineral deposits are
found (increasing the known amount of ore) or if currently unprofitable mineral
deposits become profitable ones due to either a mineral price increase or technological
improvements that make mining or processing cheaper. Mineral resources, a much
larger category than mineral reserves, are the total amount of a mineral that is not
necessarily profitable to mine today but that has some sort of economic potential.
Mining and processing ore can have considerable impact on the environment. Surface
mines can create enormous pits (see Figure Open Pit Mine) in the ground as well as
large piles of overburden and tailings that need to be reclaimed, i.e., restored to a
useful landscape. Since 1977 surface mines in U.S. are required to be reclaimed, and
commonly reclamation is relatively well done in this country. Unfortunately, surface
mine reclamation is not done everywhere, especially in underdeveloped countries, due
to lack of regulations or lax enforcement of regulations. Unreclaimed surface mines
and active surface mines can be major sources of water and sediment pollution.
Metallic ore minerals (e.g., copper, lead, zinc, mercury, and silver) commonly include
abundant sulfide, and many metallic ore deposits contain abundant pyrite (iron
sulfide). The sulfide in these minerals oxidizes quickly when exposed to air at the
surface producing sulfuric acid, called acid mine drainage. As a result streams,
ponds, and soil water contaminated with this drainage can be highly acidic, reaching
pH values of zero or less (see Figure Acid Mine Drainage)! The acidic water can leach
heavy metals such as nickel, copper, lead, arsenic, aluminum, and manganese from
mine tailings and slag. The acidic contaminated water can be highly toxic to the
ecosystem. Plants usually will not regrow in such acidic soil water, and therefore soil
erosion rates skyrocket due to the persistence of bare, unvegetated surfaces. With a
smaller amount of tailings and no overburden, underground mines usually are much
easier to reclaim, and they produce much less acid mine drainage. The major
environmental problem with underground mining is the hazardous working
environment for miners primarily caused by cave-ins and lung disease due to
prolonged inhalation of dust particles. Underground cave-ins also can damage the
surface from subsidence. Smelting can be a major source of air pollution, especially
SO> gas. The case history below examines the environmental impact of mining and
processing gold ore.
Acid Mine Drainage The water in Rio Tinto River, Spain is highly acidic
(pH = ~2) and the orange color is from iron in the water. A location along
this river has been mined beginning some 5,000 years ago primarily for
copper and more recently for silver and gold. Source: Sean Mack of NASA
via Wikimedia Commons
Sustainable Solutions to the Mineral Crisis?
Providing sustainable solutions to the problem of a dwindling supply of a
nonrenewable resource such as minerals seems contradictory. Nevertheless, it is
extremely important to consider strategies that move towards sustainability even if
true sustainability is not possible for most minerals. The general approach towards
mineral sustainability should include mineral conservation at the top of the list. We
also need to maximize exploration for new mineral resources while at the same time
we minimize the environmental impact of mineral mining and processing.
Conservation of mineral resources includes improved efficiency, substitution, and the
3 Rs of sustainability, reduce, reuse, and recycle. Improved efficiency applies to all
features of mineral use including mining, processing, and creation of mineral products.
Substituting a rare nonrenewable resource with either a more abundant nonrenewable
resource or a renewable resource can help. Examples include substituting glass fiber
optic cables for copper in telephone wires and wood for aluminum in construction.
Reducing global demand for mineral resources will be a challenge, considering
projections of continuing population growth and the rapid economic growth of very
large countries such as China, India, and Brazil. Historically economic growth is
intimately tied to increased mineral consumption, and therefore it will be difficult for
those rapidly developing countries to decrease their future demand for minerals. In
theory, it should be easier for countries with a high mineral consumption rate such as
the U.S. to reduce their demand for minerals but it will take a significant change in
mindset to accomplish that. Technology can help some with some avenues to reducing
mineral consumption. For example, digital cameras have virtually eliminated the
photographic demand for silver, which is used for film development. Using stronger
and more durable alloys of steel can translate to fewer construction materials needed.
Examples of natural resource reuse include everything at an antique store and yard
sale. Recycling can extend the lifetime of mineral reserves, especially metals.
Recycling is easiest for pure metals such as copper pipes and aluminum cans, but
much harder for alloys (mixtures of metals) and complex manufactured goods, such as
computers. Many nonmetals cannot be recycled; examples include road salt and
fertilizer. Recycling is easier for a wealthy country because there are more financial
resources to use for recycling and more goods to recycle. Additional significant
benefits of mineral resource conservation are less pollution and environmental
degradation from new mineral mining and processing as well as reductions in energy
use and waste production.
Because demand for new minerals will likely increase in the future, we must continue
to search for new minerals, even though we probably have already found many of the
“easy” targets, i.e., high-grade ore deposits close to the surface and in convenient
locations. To find more difficult ore targets, we will need to apply many technologies
including geophysical methods (seismic, gravity, magnetic, and electrical
measurements, as well as remote sensing, which uses satellite-based measurements of
electromagnetic radiation from Earth’s surface), geochemical methods (looking for
chemical enrichments in soil, water, air, and plants), and geological information
including knowledge of plate tectonics theory. We also may need to consider exploring
and mining unconventional areas such as continental margins (submerged edges of
continents), the ocean floor (where there are large deposits of manganese ore and other
metals in rocks called manganese nodules), and oceanic ridges (undersea mountains
that have copper, zinc, and lead ore bodies).
Finally, we need to explore for, mine, and process new minerals while minimizing
pollution and other environmental impacts. Regulations and good engineering
practices are necessary to ensure adequate mine reclamation and pollution reduction,
including acid mine drainage. The emerging field of biotechnology may provide some
sustainable solutions to metal extraction. Specific methods include biooxidation
(microbial enrichment of metals in a solid phase), bioleaching (microbial dissolution
of metals), biosorption (attachment of metals to cells), and genetic engineering of
microbes (creating microorganisms specialized in extracting metal from ore).
Review Questions
Exercise:
Problem:
Name some important ways mineral resources are used. Why are they important
to society?
Exercise:
Problem:
What are the major environmental issues associated with mineral resources?
Exercise:
Problem: What should society learn from the case history of gold?
Exercise:
Problem:
Why is society facing a crisis involving mineral supply and how might we work
to solve it?
References
Clugston, C. (2010) Increasing Global Nonrenewable Natural Resource Scarcity - An
Analysis, The Oil Drum. Retrieved from http://www.theoildrum.com/node/6345
Craig J, Vaughan D, and Skinner B (2011) Earth Resources and the Environment (4th
ed.). Pearson Prentice Hall, p. 92
Glossary
acid mine drainage
Surface water or groundwater that is highly acidic due to oxidation of sulfide
minerals at a mineral mine.
bioleaching of minerals
Microbial dissolution of metals.
biological processes
Processes of ore formation that involve the action of living organisms. Examples
include the formation of pearls in oysters, as well as phosphorous ore in the feces
of birds and the bones and teeth of fish.
biooxidation of minerals
Microbial enrichment of metals in a solid phase.
biosorption of minerals
Attachment of metals to cells.
black smoker
Discharge of mineral-rich waters up to 350°C from cracks in oceanic crust; these
waters precipitate a variety of metallic sulfide ore minerals that make the water
appear black.
enrichment factor
Ratio of the metal concentration needed for an economic ore deposit over the
average abundance of that metal in Earth’s crust.
genetic engineering of microbes (mineral application)
Creating microorganisms specialized in extracting metal from ore.
hydrothermal
Ore forming process involving hot salty water that dissolves metallic elements
from a large area and then precipitates ore minerals in a smaller area, commonly
along rock fractures and faults.
igneous crystallization
Ore forming process where molten rock cools to form igneous rock.
igneous rock
Forms by cooling and solidification of hot molten rock.
leaching
Using chemicals to dissolve metal from a large volume of crushed rock.
metamorphic rock
Forms when a preexisting rock changes the shape or type of minerals due to
intense heat and pressure deep within the Earth.
metamorphism
Process of ore formation that occurs deep in the earth under very high
temperature and pressure and produces several building stones, including marble
and slate, as well as some nonmetallic ore, including asbestos, talc, and graphite.
mineral
Naturally occurring inorganic solid with a defined chemical composition and
crystal structure.
mineral conservation
Method of extending the mineral supply that includes improved efficiency,
substitution, reduce, reuse, and recycle.
mineral recycling
Method of extending the mineral supply that involves processing used Minerals
into new products to prevent waste of potentially useful materials.
mineral reserves
The known amount of ore in the world.
mineral resources
Total amount of a mineral used by society that is not necessarily profitable to
Mine today but has some sort of economic potential.
mineral reuse
Method of extending the mineral supply that involves using a mineral multiple
times.
mineral substitution
Method of extending the mineral supply; involves substituting a rare
nonrenewable resource with either a more abundant nonrenewable resource or a
renewable resource.
open-pit mine
Type of surface mineral mine which commonly involve large holes that extract
relatively low-grade metallic ore.
ore
Rock with an enrichment of minerals that can be mined for profit.
ore deposit
Location with abundant ore.
placer deposit
Ore forming process where dense gold particles and diamonds are concentrated
by flowing water in rivers and at beaches.
placer mine
Type of surface mineral mine which extracts gold or diamonds from river and
beach. sediment by scooping up the sediment and then separating the ore by
density.
reclaimed mine
Mineral mine restored to a useful landscape.
rock
A solid coherent piece of planet Earth.
sedimentary processes
Processes of ore formation that occur in rivers and concentrate sand and gravel
(used in construction), as well as dense gold particles and diamonds that
weathered away from bedrock.
sedimentary rock
Forms by hardening of layers of sediment (loose grains such as sand or mud)
deposited at Earth's surface or by mineral precipitation, i.e., formation of minerals
in water from dissolved mineral matter.
slag
Glassy unwanted by-product of smelting ore.
smelting
Heating ore minerals with different chemicals to extract the metal.
strategic mineral
Mineral considered essential to a country for some military, industrial, or
commercial purpose but the country must import the mineral to meet its needs.
strip mine
Type of surface mineral mine which extracts horizontal layers of ore or rock.
surface mine
Mineral mine that occurs at Earth’s surface.
tailings
Fine-grained waste produced from processing ore.
underground mine
Mineral mine that involves a network of tunnels to access and extract the ore.
weathering
Ore forming process where soil water in a tropical rain forest environment
concentrates insoluble elements such as aluminum (bauxite) by dissolving away
the soluble elements.
Case Study: Gold: Worth its Weight?
In this module, the the large environmental impact of gold mining is
discussed.
Gold is a symbol of wealth, prestige, and royalty that has attracted and
fascinated people for many thousands of years (see Figure Native Gold).
Gold is considered by many to be the most desirable precious metal because
it has been sought after for coins, jewelry, and other arts since long before
the beginning of recorded history. Historically its value was used as a
currency standard (the gold standard) although not anymore. Gold is very
dense but also very malleable; a gram of gold can be hammered into a 1 m?
sheet of gold leaf. Gold is extremely resistant to corrosion and chemical
attack, making it almost indestructible. It is also very rare and costly to
produce. Today the primary uses of gold are jewelry and the arts,
electronics, and dentistry. The major use in electronics is gold plating of
electrical contacts to provide a corrosion-resistant conductive layer on
copper. Most gold is easily recycled except for gold plating due to
combinations with other compounds such as cyanide. About half of the
world’s gold ever produced has been produced since 1965 (see Figure
World Gold Production). At the current consumption rate today’s gold
pected to last only 20 more years.
Native Gold A
collage of 2
photos, showing 3
pieces of native
gold. The top
piece is from the
Washington
mining district,
California, and the
bottom two are
from Victoria,
Australia. Source:
Aram Dulyan via
Wikimedia
Commons
date: 31.12.2009
es ey ee es ee ee ees ee ee
2500 a World Gold Production since 1900
— . os Ea
i ravens = in metric tons per year
Accumulated world gold production in metric tons
(right vertical axis)
t
2
£
I
£
$
t
3
2
a
2
E
=
$
j
—
3
3
<
World gold production (metric tons per year)
World Gold Production World gold production from 1900 to 2009
including annual (blue line) and cumulative data (gray line) Source:
Realterm via Wikimedia Commons
There are two types of gold ore deposits: (1) hydrothermal, where magma-
heated groundwater dissolves gold from a large volume of rock and
deposits it in rock fractures and (2) placer, where rivers erode a gold ore
deposit of hydrothermal origin and deposit the heavy gold grains at the
bottom of river channels. Although gold’s resistance to chemical attack
makes it extremely durable and reusable, that same property also makes
gold difficult to extract from rock. As a result, some gold mining methods
can have an enormous environmental impact. The first discovered gold ore
was from placer deposits, which are relatively simple to mine. The method
of extracting gold in a placer deposit involves density settling of gold grains
in moving water, similar to how placer deposits form. Specific variations of
placer mining include hushing (developed by the ancient Romans where a
torrent of water is sent through a landscape via an aqueduct), sluice box
(where running water passes through a wooden box with riffles on the
bottom), panning (a hand-held conical metal pan where water swirls
around) and hydraulic (where high pressure hoses cut into natural
landscapes, see Figure Hydraulic Mining). Hydraulic mining, developed
during the California Gold Rush in the middle 1800s, can destroy natural
settings, accelerate soil erosion, and create sediment-rich rivers that later
flood due to sediment infilling the channel. The largest gold ore body ever
discovered is an ancient, lithified (i.e., hardened) placer deposit. Nearly half
of the world’s gold ever mined has come from South Africa’s
Witwatersrand deposits, which also have the world’s deepest underground
mine at about 4,000 m. To increase the efficiency of gold panning, liquid
mercury is added to gold pans because mercury can form an alloy with gold
in a method called mercury_ amalgamation. The mercury-gold amalgam is
then collected and heated to vaporize the mercury and concentrate the gold.
Although mercury amalgamation is no longer used commercially, it is still
used by amateur gold panners. Unfortunately, considerable mercury has
been released to the environment with this method, which is problematic
because mercury bioaccumulates and it is easily converted to
methylmercury, which is highly toxic.
Today most gold mining is done by a method called heap hing, where
cyanide-rich water percolates through finely ground col ore and dissolves
the gold over a period of months; eventually the water is collected and
treated to remove the gold. This process revolutionized gold mining
because it allowed economic recovery of gold from very low-grade ore
(down to 1 ppm) and even from gold ore tailings that previously were
considered waste. On the other hand, heap leaching is controversial because
of the toxic nature of cyanide. The world’s largest cyanide spill to date
occurred at Baia Mare in northern Romania (see Figure Baia Mare). In
January 2000 after a period of heavy rain and snowmelt, a dam surrounding
a gold tailings pond collapsed and sent into the drainage basin of the
Danube River 100,000 m? (100 million liters) of water with 500 - 1,000
ppm cyanide] footnote], killing more than a thousand metric tons of fish (see
Figure Baia Mare Cyanide Spill). Considering the large environmental
impact of gold mining, this may take some of the glitter from gold.
The U.S. EPA allows no more than 0.2 ppm cyanide in drinking water.
Industrial hot spots
Tisza river basin
aaa N 400 km
||
Baia Mare Map of Tisza River drainage basin with pollution hot spots
including Baia Mare, Romania, which is the location of a cyanide spill
disaster in 2000 Source: United Nations Environment Program -
GRID-Arendal
Baia Mare Cyanide Spill Dead
fish from cyanide spill disaster Baia
Mare, Romania, the location of a in
2000 Source: Toxipedia
Glossary
Heap leaching
Method of gold mining where cyanide-rich water percolates through
finely ground gold ore and dissolves the gold over a period of months;
eventually the water is collected and treated to remove the gold.
Hushing
Method of placer mining developed by the ancient Romans where a
torrent of water is sent through a landscape via an aqueduct.
Hydraulic mining
Method of placer mining where high pressure hoses cut into natural
landscapes.
Mercury amalgamation
Method of gold panning where liquid mercury is added to gold pans
because mercury can form an alloy with gold.
Panning
Method of placer mining where water in a hand-held conical metal pan
swirls around.
Sluice box
Method of placer mining where running water passes through a
wooden box with riffles on the bottom.
Environmental and Resource Economics - Chapter Introduction
This chapter gives an overview of a few of the key ideas and economic
theories that help us understand where environmental problems come from
and what makes something a problem that actually needs to be fixed.
a,
Source: The NEED Project
Introduction
The field of environmental and natural resource economics sounds to many
like an oxymoron. Most people think economists study money, finance, and
business—so what does that have to do with the environment? Economics
is really broadly defined as the study of the allocation of scarce resources.
In other words, economics is a social science that helps people understand
how to make hard choices when there are unavoidable tradeoffs. For
example, a company can make and sell more cars, which brings in revenue,
but doing so also increases production costs. Or a student can choose to
have a part-time job to reduce the size of the loan she needs to pay for
college, but that reduces the time she has for studying and makes it harder
for her to get good grades. Some economists do study business, helping
companies and industries design production, marketing, and investment
strategies that maximize their profits. Other economists work to understand
and inform the choices individuals make about their investments in
education and how to divide their time between work, leisure, and family in
order to make themselves and their families better off. Environmental and
natural resource economists study the tradeoffs associated with one of the
most important scarce resources we have—nature.
Economists contribute to the study of environmental problems with two
kinds of work. First, they do normative studies of how people should
manage resources and invest in environmental quality to make themselves
and/or society as well off as possible. Second, they do positive analyses of
how human agents—individuals, firms, and so forth—actually do behave.
Normative studies give recommendations and guidance for people and
policy makers to follow. Positive studies of human behavior help us to
understand what causes environmental problems and which policies are
most likely to work well to alleviate them.
This chapter gives an overview of a few of the key ideas that have been
developed in this field. First, we will learn the economic theories that help
us understand where environmental problems come from and what makes
something a problem that actually needs to be fixed. This section of the
chapter will introduce the concepts of externalities, public goods, and open
access resources, and explain how in situations with those features we often
end up with too much pollution and excessive rates of natural resource
exploitation. Second, we will learn the tools economists have developed to
quantify the value of environmental amenities. It is very difficult to identify
a monetary value for things like clean air and wildlife, which are not traded
in a marketplace, but such value estimates are often helpful inputs for
public discussions about environmental policies and investments. Third, we
will discuss a set of approaches economists use to evaluate environmental
policies and projects. We want to design policies that are “good,” but what
exactly does that mean? Finally, we will learn about the different policy
tools that can be used to solve problems of excess environmental
degradation and resource exploitation, including a set of incentive policies
that were designed by economists to work with rather than against the way
that people really behave, and we will discuss the strengths and weaknesses
of those different tools.
Glossary
normative analysis
A study of how things should be.
positive analysis
A study of how things are.
Tragedy of the Commons
In this module, the way economists think about whether an outcome is good
is explored and some of the features of natural resources and environmental
quality that often trigger problematic human behaviors related to the
environment are described.
Learning Objectives
After reading this module, students should be able to
e know how economists define environmental outcomes that make
society as well off as possible.
e understand what externalities are, and how they can lead to outcomes
with too much pollution and resource exploitation.
¢ be able to define public goods and common-property resources, and
understand how those things are prone to under-provision and over-
exploitation, respectively.
Introduction
To identify and solve environmental problems, we need to understand what
situations are actually problems (somehow formally defined) and what
circumstances and behaviors cause them. We might think that it is easy to
recognize a problem—pollution is bad, saving natural resources is good.
However, critical thinking often reveals snap judgments to be overly
simplistic. Some examples help to illustrate this point.
e Running out! Oil is a depletable resource, and many people worry that
rapid extraction and use of oil might cause us to run out. But would it
really be a bad thing to use up all the oil as long as we developed
alternative energy technologies to which we could turn when the oil
was gone? Is there any intrinsic value to keeping a stock of oil unused
in the ground? Running out of oil someday may not be a problem.
However, subsidies for oil extraction might cause us to run out more
quickly than is socially optimal. Other inefficiencies arise if multiple
companies own wells that tap the same pool of oil, and each ends up
racing to extract the oil before the others can take it away—that kind
of race can increase total pumping costs and reduce the total amount of
oil that can be gleaned from the pool.
e Biological pollution! Horror stories abound in the news about the
havoc raised by some nonnative animal and plant species in the United
States. Zebra mussels clog boats and industrial pipes, yellow star
thistle is toxic to horses and reduces native biodiversity in the
American West, and the emerald ash borer kills ash trees as it marches
across the landscape. From the current tone of much media and
scientific discourse about nonnative species, one could conclude that
all nonnative species are problems. But does that mean we should
forbid farmers in the U.S from growing watermelons, which come
from Africa? Or should we ship all the ring-necked pheasants back to
Eurasia whence they originally came, and tell North Dakota to choose
a new State bird? The costs and benefits of nonnative species vary
greatly — one policy approach is not likely to apply well to them all.
This section first explains the way economists think about whether an
outcome is good. Then it describes some of the features of natural resources
and environmental quality that often trigger problematic human behaviors
related to the environment.
Efficiency and Deadweight Loss
Ask anyone who lived during the centrally-planned, nonmarket economy
years of the Soviet Union—markets are very good at many things. When a
product becomes scarcer or more costly to produce we would like to send
signals to consumers that would cause them to buy less of that thing. If an
input is more valuable when used to produce one good than another, we
would like to send signals to firms to make sure that input is put to its best
use. If conditions are right, market prices do these useful things and more.
Markets distribute inputs efficiently through the production side of the
economy: they ensure that plant managers don’t need to hoard inputs and
then drive around bartering with each other for the things they need to make
their products, and they arrange for efficient quantities of goods to be
produced. Markets also distribute outputs among consumers without
surpluses, shortages, or large numbers of bathing suits being foisted upon
consumers in Siberia.
Economists mean something very specific when they use the word
efficient. In general, an allocation is efficient if it maximizes social well-
being, or welfare. Traditional economics defines welfare as total net
benefits—the difference between the total benefits all people in society get
from market goods and services and the total costs of producing those
things. Environmental economists enhance the definition of welfare. The
values of environmental goods like wildlife count on the “benefit” side of
net benefits and damages to environmental quality from production and
consumptive processes count as costs.
Under ideal circumstances, market outcomes are efficient. In perfect
markets for regular goods, goods are produced at the point where the cost to
society of producing the last unit, the marginal cost, is just equal to the
amount a consumer is willing to pay for that last unit, the marginal benefit,
which means that the net benefits in the market are maximized. Regular
goods are supplied by industry such that supply is equivalent to the
marginal production costs to the firms, and they are demanded by
consumers in such a way that we can read the marginal benefit to
consumers off the demand curve; when the market equilibrates at a price
that causes quantity demanded to equal quantity supplied at that price
(Qmarket in Figure Market Equilibrium), it is also true that marginal
benefit equals marginal cost.
Supply = MCprivate
Price
Demand = MBprivate
Quantity of good
6
Market Equilibrium A private market equilibrates at a price such that
the quantity supplied equals the quantity demanded, and thus private
marginal cost equals private marginal benefit. Source: Amy Ando
Even depletable resources such as oil would be used efficiently by a well-
functioning market. It is socially efficient to use a depletable resource over
time such that the price rises at the same rate as the rate of interest.
Increasing scarcity pushes the price up, which stimulates efforts to use less
of the resource and to invest in research to make “backstop” alternatives
more cost-effective. Eventually, the cost of the resource rises to the point
where the backstop technology is competitive, and the market switches
from the depletable resource to the backstop. We see this with copper; high
prices of depletable copper trigger substitution to other materials, like fiber
optics for telephone cables and plastics for pipes. We would surely see the
same thing happen with fossil fuels; if prices are allowed to rise with
scarcity, firms have more incentives to engage in research that lowers the
cost of backstop technologies like solar and wind power, and we will
eventually just switch.
Unfortunately, many conditions can lead to market failure such that the
market outcome does not maximize social welfare. The extent to which net
benefits fall short of their potential is called deadweight loss. Deadweight
loss can exist when not enough of a good is produced, or too much of a
good is produced, or production is not done in the most cost-effective (least
expensive) way possible, where costs include environmental damages.
Some types of market failures (and thus deadweight loss) are extremely
common in environmental settings.
Externalities
In a market economy, people and companies make choices to balance the
costs and benefits that accrue to them. That behavior can sometimes yield
outcomes that maximize total social welfare even if individual agents are
only seeking to maximize their own personal well-being, because self-
interested trades lead the market to settle where aggregate marginal benefits
equal aggregate marginal costs and thus total net benefits are maximized.
However, people and companies do not always bear the full costs and
benefits associated with the actions they take. When this is true economists
say there are externalities, and individual actions do not typically yield
efficient outcomes.
A negative externality is a cost associated with an action that is not borne
by the person who chooses to take that action. For example, if a student
cheats on an exam, that student might get a higher grade. However, if the
class is graded on a curve, all the other students will get lower grades. And
if the professor learns that cheating happened, she might take steps to
prevent cheating on the next exam that make the testing environment more
unpleasant for all the students (no calculators allowed, no bathroom breaks,
id checks, etc.). Negative externalities are rampant in environmental
settings:
¢ Companies that spill oil into the ocean do not bear the full costs of the
resulting harm to the marine environment, which include everything
from degraded commercial fisheries to reduced endangered sea turtle
populations).
¢ Commuters generate emissions of air pollution, which lowers the
ambient quality of the air in areas they pass through and causes health
problems for other people.
¢ Developers who build houses in bucolic exurban settings cause habitat
fragmentation and biodiversity loss, inflicting a cost on the public at
large.
Negative Externality: Smog A NASA photograph of the atmosphere
over upstate New York, with Lake Eire (top) and Lake Ontario
(bottom) featured. Both natural, white clouds and man-made smog
(grey clouds below) are visible. The smog is an example of a negative
externality, as the cost of the aeons is pone ge ake in awe
region, not at ue ee Source: , age Science and Analysis
In situations where an action or good has a negative externality, the private
marginal cost that shapes the behavior of an agent is lower than the
marginal cost to society as a whole, which includes the private marginal
cost and the external environmental marginal cost. The efficient outcome
would be where the social marginal cost equals the social marginal benefit
(labeled Qosficient in Figure Inefficiency from Negative Externality).
Unfortunately, the free-market outcome (labeled Qyarket in Figure
Inefficiency from Negative Externality) will tend to have more of the
good or activity than is socially optimal because the agents are not paying
attention to all the costs. Too much oil will be shipped, and with insufficient
care; people will drive too many miles on their daily commutes; developers
will build too many new homes in sensitive habitats. Thus, there is
deadweight loss (the shaded triangle in the figure); the marginal social cost
associated with units in excess of the social optimum is greater than the
marginal benefit society gets from those units. Public policy that reduces
the amount of the harmful good or activity could make society as a whole
better off.
MCyociat = MCexternal + MCorivate
Quantity of
Good
Qefficient Qmarket
Inefficiency from Negative Externality When there is a
negative externality, the market equilibrates where the total
social marginal cost exceeds the marginal benefit of the last
unit of a good and society is not as well off as it could be if less
were produced. Source: Amy Ando
Conversely, a positive externality is a benefit associated with an action that
is not borne by the person who chooses to take that action. Students who get
flu shots in October, for example, gain a private benefit because they are
less likely to get the flu during the winter months. However, their
classmates, roommates, and relatives also gain some benefit from that
action because inoculated students are less likely to pass the flu along to
them. Positive externalities exist in the world of actions and products that
affect the environment:
e A homeowner who installs a rain barrel to collect unchlorinated
rainwater for her garden also improves stream habitat in her watershed
by reducing stormwater runoff.
e A delivery company that re-optimizes its routing system to cut fuel
costs also improves local air quality by cutting its vehicle air pollution
emissions.
e A farmer who plants winter cover crops to increase the productivity of
his soil will also improve water quality in local streams by reducing
erosion.
In situations where an action or good has a positive externality, the private
marginal benefit that shapes the behavior of an agent is lower than the
marginal benefit to society as a whole, which includes the private marginal
benefit and the external environmental marginal benefit. The efficient
outcome would be where the social marginal cost equals the social marginal
benefit (labeled Qorricient in Figure Positive Externality). In the presence of
a positive externality, the free-market outcome will tend to promote less of
the good or activity than is socially optimal because the agents do not reap
all the benefits. Too few rain barrels will be installed; not enough delivery
routes will be re-optimized; too few acres of agricultural fields will have
cover crops in the winter months. Again there is deadweight loss (the
shaded triangle in the figure), but this time because the marginal social
benefit associated with some of the units not produced would have been
greater than the marginal costs of producing them. Just because an
externality is positive rather than negative doesn’t mean there isn’t a
problem; public policy could still make society as a whole better off.
MCorivate
MBsocial = MBexternal + MBprivate
Quantity of good
Qmarket Qefficient
Positive Externality When there is a a positive externality, the market
equilibrates where the total social marginal benefit exceeds the
marginal cost of the last unit of a good and society is not as well off as
it could be if more were produced. Source: Amy Ando
Public Goods and Common-pool Resources
Market outcomes are almost never efficient in two broad kinds of cases:
public goods and common-pool resources. The market failures in these
settings are related to the problems we saw with negative and positive
externalities.
A pure public good is defined as being nonexclusive and nonrival in
consumption. If something is nonexclusive, people cannot be prevented
from enjoying its benefits. A private house is exclusive because doors,
windows, and an alarm system can be used to keep nonowners out. A
lighthouse, on the other hand, is non-exclusive because ships at sea cannot
be prevented from seeing its light. A good that is nonrival in consumption
has a marginal benefit that does not decline with the number of people who
consume it. A hot dog is completely rival in consumption: if I eat it, you
cannot. On the other hand, the beauty of a fireworks display is completely
unaffected by the number of people who look at it. Some elements of the
environment are pure public goods:
e Clean air in a city provides health benefits to everyone, and people
cannot be prevented from breathing
e The stratospheric ozone layer protects everyone on earth from solar
UV radiation
The efficient amount of a public good is still where social marginal benefit
equals the marginal cost of provision. However, the social marginal benefit
of one unit of a public good is often very large because many people in
society can benefit from that unit simultaneously. One lighthouse prevents
all the ships in an area from running aground in a storm. In contrast, the
social marginal benefit of a hot dog is just the marginal benefit gained by
the one person who gets to eat it.
Society could figure out the efficient amount of a public good to provide—
say, how much to spend on cleaner cars that reduce air pollution in a city.
Unfortunately, private individuals acting on their own are unlikely to
provide the efficient amount of the public good because of the free rider
problem. If my neighbors reduce pollution by buying clean electric cars or
commuting via train, I can benefit from that cleaner air; thus, I might try to
avoid doing anything costly myself in hopes that everyone else will clean
the air for me. Evidence suggests that people do not behave entirely like
free riders — they contribute voluntarily to environmental groups and public
radio stations. However, the levels of public-good provision generated by a
free market are lower than would be efficient. The ozone layer is too thin;
the air is too dirty. Public goods have big multilateral positive externality
problems.
In contrast, a common-pool resource (also sometimes called an open-
access resource) suffers from big multilateral negative externality problems.
This situation is sometimes called the “tragedy of the commons.” Like
public goods, common-pool resources are nonexcludable. However, they
are highly rival in use. Many natural resources have common-pool features:
e Water in a river can be removed by anyone near it for irrigation,
drinking, or industrial use; the more water one set of users removes,
the less water there is available for others.
¢ Swordfish in the ocean can be caught by anyone with the right boat
and gear, and the more fish are caught by one fleet of boats, the fewer
remain for other fishers to catch.
e Old growth timber in a developing country can be cut down by many
people, and slow regrowth means that the more timber one person cuts
the less there is available for others.
One person’s use of a common-pool resource has negative effects on all the
other users. Thus, these resources are prone to overexploitation. One person
in Indonesia might want to try to harvest tropical hardwood timber slowly
and sustainably, but the trees they forebear from cutting today might be cut
down by someone else tomorrow. The difficulty of managing common-pool
resources is evident around the world in rapid rates of tropical
deforestation, dangerous overharvesting of fisheries (see Case study:
Marine Fisheries), and battles fought over mighty rivers that have been
reduced to dirty trickles.
The tragedy of the commons occurs most often when the value of the
resource is great, the number of users is large, and the users do not have
social ties to one another, but common-pool resources are not always
abused. Elinor Ostrom’s Nobel prize-winning body of work, for example,
has studied cases of common-pool resources that were not over-exploited
because of informal social institutions.
Review Questions
Exercise:
Problem: What does it mean for an outcome to be efficient?
Exercise:
Problem:
How do externalities cause market outcomes not to be efficient?
Exercise:
Problem:
How are the free rider problem and the common pool resource
problem related to basic problems of externalities?
Glossary
common pool resource
A resource that is open to all users, but which is highly rival in use.
cost-effective
As inexpensive as possible; cost minimizing.
deadweight loss
The extent to which net benefits are lower than they could be.
efficient
Having the feature that net benefits are maximized.
free rider
A person who does not contribute to a public good in hopes that they
can benefit from provision by other people.
marginal benefit
The additional benefit of doing one more unit of something.
marginal cost
The additional cost of doing one more unit of something.
market failure
A condition that causes a market not to yield the efficient outcome.
negative externality
A cost that is borne by someone who did not agree to the activity that
caused the cost.
net benefits
The difference between total benefits and total costs.
normative analysis
A study of how things should be.
positive analysis
A study of how things are.
positive externality
A benefit that accrues to someone who did not agree to the activity that
caused the benefit.
public good
A good with two features: (i) it has a benefit that does not diminish
with the number of people enjoying it, and (ii) no one can be excluded
from consuming it.
welfare
Broadly defined, welfare is well-being.
Case Study: Marine Fisheries
In this module,the state of marine fisheries and Individual tradable quotas
(ITQ) are described.
Fisheries are classic common-pool resources. The details of the legal
institutions that govern access to fisheries vary around the globe. However,
the physical nature of marine fisheries makes them prone to
overexploitation. Anyone with a boat and some gear can enter the ocean.
One boat’s catch reduces the fish available to all the other boats and reduces
the stock available to reproduce and sustain the stock available in the
following year. Economic theory predicts that the market failure associated
with open access to a fishery will yield socially excessive levels of entry
into the fishery (too many boats) and annual catch (too many fish caught)
and inefficiently low stocks of fish (Beddington, Agnew, & Clark, 2007).
Overfished Stocks (49) - n 2011
New England:
. Atlantic cod - Georges Bank
. Atlantic halibut
. Atlantic salmon?
. Atlantic wolffish?
. Ocean pout
. Smooth skate
. Thorny skate
. White hake
S. Yellowtail flounder - Georges Bank
10. Yellowtail flounder - Southern New England/Mid-Atlantic
11. Yellowtail flounder - Cape Cod/Gulf of Maine
il 12. Windowpane - Gulf of Maine/Georges Bank
13. Winter flounder - Southern New England/Mid-Atlantic
14, Winter flounder - Georges Bank
15. Witch flounder Highly Migrato
1
2
North Pacific: :
1. Blue king crab - Pribilof Islands 5
2. Southern Tanner crab - Bering Sea 6
%
8
Pacific:
1. Canary rockfish y { Species:
2. Cowcod - 1. Albacore - North Atlantic?
3. Petrale sole 2. Blacknose shark
4. Chinook salmon - California 3. Blue marlin - Atlantic?
Central Valley: Sacramento 4. Bluefin tuna - West Atlantic?
Hh)? 5. Dusky shark
5. Coho salmon - Washington 6. Porbeagle shark
Coast: Queets: < 7. Sandbar shark
6. Coho salmon - Washington 8. White marlin - Atlantic?
Coast: Western Strait of Juan de 9. Scalloped hammerhead -
Fi 2
Atlantic
Mid-Atlantic:
1. Butterfish - Atlantic
South Atlantic:
7. Yelloweye rockfish
aa 1. Black Sea Bass
wy 2. Pink Shrimp
2 3. Red Grouper
Western Pacific : 4, Red Porgy
I. Seamount Groundfish Complex - Hancock Seamount Gulf of Mexico: 5. Red Snapper
1. Ga 6. Snowy Grouper
2. Gray triggerfish
3. Greater amberjack .
4. Red snapper " way. Caribbean:
1. Grouper Unit 1
2. Grouper Unit 2
3. Grouper Unit 4
U.S. Department of Commerce 4. Queen conch
National Oceanic and Atmospheric 1, Non-FSSI stock
7 Sin,
Z © ‘,
ws parriaeecnes ai 2, Stock is fished by U.S, and International fleets
‘ 7
* National Marine Fisheries Service
ice of Sustainable Fisheries
Source: National Oceanic and Atmospheric Administration
Unfortunately, the state of fisheries around the globe seems to indicate that
the predictions of that theory are being borne out. Bluefin tuna are in danger
of extinction. Stocks of fish in once-abundant fisheries such as North
Atlantic cod and Mediterranean swordfish have been depleted to
commercial (and sometimes biological) exhaustion (Montaigne, 2007).
Scientists have documented widespread collapse of fish stocks and
associated loss of marine biodiversity from overfishing; this devastates the
ability of coastal and open-ocean ecosystems to provide a wide range of
ecosystem services such as food provisioning, water filtration, and
detoxification (Worm et al., 2006). Scholars have documented isolated
cases such as the “lobster gangs” of coastal Maine where communal
informal management prevented overexploitation of the resource (Acheson,
1988), but such cases are the exception rather than the rule.
Early efforts to control overfishing used several kinds of regulations on
quotas, fishing effort, and gear. For example, fishing boats are forbidden in
some places from using conventional longlines because that gear yields
high levels of bycatch and kills endangered leatherback turtles. Some forms
of fishery management limit the number of fish that can be caught in an
entire fishery. Under a total allowable catch (TAC) system, fishers can fish
when and how they want, but once the quota for the fishery has been met,
fishing must stop until the next season. Unfortunately, TAC policies do not
solve the underlying problem that fishermen compete for the fish, and often
yield perverse incentives and undesirable outcomes such as
overcapitalization of the industry (Beddington, Agnew, & Clark, 2007) and
races between fishing boat crews to catch fish before the quota is reached.
In the well-known case of the Alaskan halibut fishery, the race became so
extreme that the fishing season was reduced to a single 24-hour mad dash;
given that fish are perishable, this temporal clumping of the catch is not a
desirable outcome.
Marine Fisheries: Fishing Boats
Alaskan waters have been fished by
people for thousands of years, but they
are under pressure from modern fishing
technologies and large-scale extraction.
Source: National Oceanic and
Atmospheric Administration
Resource economists developed the idea of a tradable permit scheme to
help manage fisheries. Individual tradable quota (ITQ) schemes are cap-
and-trade policies for fish, where total catch is limited but fishers in the
fishery are given permits that guarantee them a right to a share of that catch.
Players in the fishery can sell their quota shares to each other (helping the
catch to flow voluntarily to the most efficient boats in the industry) and
there is no incentive for captains to buy excessively large boats or fish too
rapidly to beat the other boats to the catch. ITQ policies have rationalized
the Alaskan halibut fishery completely: the fish stock is thriving,
overcapitalization is gone, and the fish catch is spread out over time (Levy,
2010). ITQs have also been implemented in the fisheries of New Zealand,
yielding large improvements in the biological status of the stocks (Annala,
1996). There is some general evidence that ITQ systems have been
relatively successful in improving fishery outcomes (Costello, Gaines, &
Lynham et al. 2008), though other research implies that evidence of the
superiority of the ITQ approach is more mixed (Beddington 2007) Scholars
and fishery managers continue to work to identify the details of ITQ
management that make such systems work most effectively, and to identify
what needs to be done to promote more widespread adoption of good
fishery management policy worldwide.
References
Acheson, J. M. (1988). The Lobster Gangs of Maine. Lebanon, NH:
University of New England Press.
Annala, J. H. (1996). New Zealand’s ITQ system: have the first eight years
been a success or a failure? Reviews in Fish Biology and Fisheries. 6(1),
43-62. doi: 10.1007/BF00058519
Beddington, J. R., Agnew, D.J., & Clark, C. W. (2007). Current problems in
the management of marine fisheries. Science, 316(5832), 1713-1716.
doi:10.1126/science.1137362
Costello, C., Gaines, S. D., & Lynham, J. (2008). Can catch shares prevent
fisheries collapse? Science, 321(5896), 1678 — 1681.
doil0.1126/science.1159478
Levy, S. (2010). Catch shares management. BioScience, 60(10), 780-785.
doi:10.1525/bio0.2010.60.10.3
Montaigne, F. (2007, April). Still waters, the global fish crisis. National
Geographic Magazine. Retrieved from
http://ngm.nationalgeographic.com/print/2007/04/global-fisheries-
crisis/montaigne-text.
Worm, B., Barbier, E. B., Beaumont, N., Duffy, J. E., Folke, C., Halpern, B.
S., Hackson, J. B. C., Lotze, H. K., Micheli, F., Palumbi, S. R., Sala, E.,
Selkoe, K. A., Stachowicz, J. J., & Watson, R. (2006). Impacts of
biodiversity loss on ocean ecosystem services. Science, 314(5800), 787 —
790. doi:10.1126/science.1132294
Environmental Valuation
In this module, the following topics will be covered: 1) estimates of the
values of environmental goods in dollar terms, and 2) the strengths and
weaknesses of valuation methods in all three parts of the environmental
valuation toolkit.
Learning Objectives
After reading this module, students should be able to
1. understand why it might be useful to develop estimates of the values of
environmental goods in dollar terms.
2. know the difference between the two economic measures of value,
willingness to pay and willingness to accept.
3. be familiar with valuation methods in all three parts of the
environmental valuation toolkit: direct, revealed preference, and stated
preference methods.
4. understand the strengths and weaknesses of those valuation methods.
Use Values
Externality, public good, and common-pool resource problems yield
suboptimal levels of environmental quality and excessive rates of resource
exploitation. Many factors complicate the process of deciding what to do
about these problems. One is that environmental goods are not traded in any
marketplace, and hence analysts struggle to identify quantitative measures
of their values to society.
Environmental valuation is controversial. Some environmentalists object to
efforts to place dollar values on elements of the environment that might be
viewed as priceless. Such values are important, however, for making sure
that society does not fail to take the value of nature into account when
making policy and investment choices. All U.S. government regulations, for
example, are subjected to benefit-cost analyses to make sure that
government actions don’t inadvertently make society worse off (see Module
Evaluating Projects and Policies). If we do not have dollar values for the
environmental benefits of things like clean water and air, then estimates of
the benefits of pollution control will be consistently lower than the true
social benefits, and government policy will chronically underinvest in
efforts to control pollution.
Environmental and natural resource economists have worked for decades to
develop valuation methods that can be used to generate reasonable
estimates of the dollar values of environmental amenities. Thousands of
journal articles have been published in this effort to refine valuation
methodology. In the early years of valuation studies, most of the work was
focused on generating estimates of the social values of water and air quality.
Over time, economists broadened their focus to study how to value a
broader range of amenities such as wetland habitat and endangered species.
The United Nations launched an international effort in 2000 called the
Millennium Ecosystem Assessment which was to evaluate the current state
of earth’s ecosystems (and the services that flow from nature to humans)
and identify strategies for conservation and sustainable use. Reports from
this effort) have helped scientists and policy makers develop a new
framework for thinking about how nature has value to humans by providing
a wide range of ecosystem services. Since then, a surge of multidisciplinary
research has emerged to quantify the physical services provided by the
environment and estimate the values to humanity of those services.
Economists recognize two broad categories of environmental values: use
and non-use. Use values flow from services that affect people directly, such
as food production, flood regulation, recreation opportunities, and potable
water provision. Non-use values are less tangible: the desire for endangered
tigers to continue to exist even on the part of people who will never see
them in the wild; concern about bequeathing future generations a planet
with healthy fish populations; a sense that people have an ethical
responsibility to be good stewards of the earth. Economic valuation
methods exist to capture all of these environmental values.
Use Value: Recreational Angler A fisherman takes advantage of the
use value of the natural environment of Four Springs Lake, Tasmania.
-£ io fa Dias tin
Source: Photo by Peripitus
Non-use Value: Sumatran Tiger
Although wild tigers do not directly
impact people living in the United
States, many Americans wish for the
species to continue existing in their
natural environment. This is an
example of a non-use value. Source:
Photo by Nevit Dilman
Willingness to Pay/Accept
Economists use measures of value that are anthropocentric, or human
centered. A rigorous body of theory about consumer choice lies beneath
those measures. Mathematical complexity can make that theory seem like
unreliable trickery, but in truth, consumer theory rests on only a very small
number of fundamental assumptions:
¢ People have preferences over things.
¢ People are able to rank any two bundles of goods to identify which one
they prefer.
e People are rational in that they will choose the bundle they prefer (over
bundles they do not prefer) if they can afford it.
Those uncontroversial axioms are actually enough to derive all the results
economists use when working with valuation methodology. However, the
derivations are easier and sometimes more intuitive with a little more
structure added to our hypothetical consumer choice problem:
e People face budget constraints (total expenditures can’t exceed their
income).
e People make choices to make themselves as well off as possible
(“maximize their utility”) within the rationing forced by their budget
constraints.
This framework yields two ways to think about the values of changes to the
quality or quantity of environmental goods. Consider first a situation where
we are trying to determine the value of a project that yields an
environmental improvement—say, for example, water in the Chicago River
will be cleaner. The social benefit of that project turns out to be what people
are willing to pay for it. The second measure of value is appropriate if we
want to measure the value of environmental goods that will be lost or
degraded by a deleterious change—say, for example, climate change
leading to the extinction of polar bears. In that context, the value of the
change is given by the amount of money you would have to pay people in
order to make them willing to accept it.
“Willingness to pay” (WTP) is a budget-constrained measure of a change
in welfare; a person cannot be willing to pay more money for a change than
they have income. In contrast, “willingness to accept” (WTA) is nota
budget constrained measure of value—you might have to increase a
person’s income many times over in order to fully compensate them for the
loss of an environmental amenity they hold dear—and can theoretically
approach infinity. Empirical studies tend to find that WTA value estimates
are larger than equivalent estimates of WTP.
Analysts usually choose whether to use WTA or WTP approaches as a
function of the context of the analysis. The “right” measure to use may
depend on whether you want value estimates to inform a policy that would
improve conditions relative to the current legal status quo, or to understand
the consequences of a change that would cause deterioration of some
environmental good citizens currently enjoy. Another factor in choosing a
valuation method is that WTP is budget constrained while WTA is not.
WTP estimates of value tend to be lower in places where people have lower
incomes. That variation captures a realistic pattern in the size of willingness
to pay for environmental improvements. However, equity problems clearly
plague a study that concludes, for example, that improvements in air quality
are more valuable to society if they happen in rich areas rather than poor.
All valuation methodologies—WTP and WTA—are designed to estimate
values of fairly small changes in the environment, and those values are
often setting-specific. Careful analysts can do benefit transfer studies in
which they use the results of one valuation study to inform value estimates
in a different place. However, such applications must be carried out
carefully. The value of a unit change in a measure of environmental
integrity is not an immutable constant, and the values of very large changes
in either quantity or quality of an environmental amenity usually cannot be
estimated. A cautionary example is an influential but widely criticized
paper published in Nature by Robert Costanza and colleagues that carried
out sweeping benefit transfer estimates of the total social values of a
number of Earth’s biomes (open oceans, forests, wetlands, etc.). The
resulting estimates were too large to be correct estimates of WTP because
they exceeded the value of the whole world’s GDP, and too small to be
correct estimates of WTA because life on earth would cease to exist if
oceans disappeared, so WTA for that change should be infinity (Costanza et
al, 197).
An Economist’s Environmental Valuation Toolkit: Direct,
Revealed Preference, and Stated Preference Methods
Early work on environmental valuation estimated the benefits of improved
environmental quality using direct methods that exploit easily obtained
information about the monetary damage costs of pollution. These methods
are still sometimes used (most often by people who are not environmental
economists) because of their simple intuitive appeal. An analyst can
measure costs associated with pollution; the benefits of environmental
cleanup are then the reductions in those costs. Following are some
examples:
e Production damage measures: Pollution has a deleterious effect on
many production processes. For example, air pollution lowers corn
yields, thus increasing the cost of producing a bushel of corn. An
analyst could try to measure the benefits of eliminating air pollution by
calculating the increase in net social benefits that would flow from the
com market as a result of higher yields.
e Avoided cost measures: Environmental degradation often forces people
to spend money on efforts to mitigate the harm caused by that
degradation. One benefit of reversing the degradation is not having to
spend that money on mitigation—the avoided cost. For example,
hydrological disruption from impervious surfaces in urban areas forces
cities to spend money on expensive storm sewer infrastructure to try to
reduce floods. A benefit of installing rain gardens and green roofs to
manage stormwater might be avoided storm sewer infrastructure costs.
e Health cost measures: Pollution has adverse effects on human health.
For example, toxic chemicals can cause cancer, and ground level
ozone causes asthma. Some measures of the damages caused by
pollution simply count the financial costs of such illnesses, including
the costs of cancer treatment and lost wages from adults missing work
during asthma attacks.
These measures seem appealing, but are in fact deeply problematic. One of
the most serious problems with direct measures is that they often yield
woefully incomplete estimates of the benefits of environmental cleanup.
Consider the example of cancer above. Suppose a woman gets cancer from
drinking contaminated well water. By the time her illness is diagnosed, the
cancer is so advanced that doctors can do little to treat her, and she dies a
few months later. The medical expenditures associated with this illness are
not very large; she and her family would surely have been willing to pay
much more money to have eliminated the toxins so she did not ever get
sick. The direct health cost measure of the benefits of cleaning up the
contaminated water is a serious underestimate of the true benefit to society
of that environmental improvement.
A second set of valuation tools called revealed preference methods work
to estimate WTP for environmental amenities and quality by exploiting data
on actual behaviors and market choices that are related to the environmental
good in question. People reveal their WTP for environmental goods with
their actions. Three examples of such methods are below.
e Hedonic price analysis: We often cannot observe individuals taking
direct action to change the quality of the environment to which they
are exposed in a given location because they simply cannot effect such
change; no one person, for example, can reduce the concentration of
fine particles in the air near his house. We do, however, observe
market data about the choices people make about where to live. If two
houses are otherwise identical but one house is situated in a place with
much cleaner air than the other, the benefit of breathing cleaner air will
get capitalized in the value of that house. All else equal,
neighborhoods with better environments will have more expensive
homes. Analysts can gather data on housing prices and house
characteristics (both environmental and nonenvironmental) and use a
statistical analysis to estimate marginal WTP for elements of
environmental quality that vary among the houses in the data set. The
hedonic price analysis approach has been used to value amenities
such as air quality, hazardous waste site cleanup, and open space.
e Hedonic wage analysis: Some forms of pollution cause people to face
higher risk of death in any given year. Thus, one important goal of
valuation is to estimate a dollar value of reduced mortality resulting
from pollution cleanup. Except in the movies, we rarely observe
people choosing how much money they are willing to pay to save a
specific person from certain death. However, all of us make choices
every day that affect our risk of death. One important choice is which
job to accept. Elementary school teachers face little job-related
mortality risk. In contrast, coal miners, offshore oil rig workers, and
deep sea fishermen accept high rates of accidental death when they
take their jobs. By analyzing data on wage rates and worker death rates
in a variety of different industries, we can estimate WTP to reduce the
risk of death. Using such hedonic wage analysis, economists have
developed measures of the value of a statistical life (VSL), which can
be applied to physical estimates of reductions in pollution-related
deaths to find the benefits of reduced mortality.
e Travel cost analysis: Many natural amenities, such as forests, lakes,
and parks are enjoyed by the public free of charge. While there is no
formal market for “hours of quality outdoor recreation,” people do
incur costs associated with such recreation—gas purchased to drive to
the site, hotel expenses for overnight trips, and the opportunity cost of
the time spent on the trip. If environmental quality is valued, people
will be willing to pay higher travel costs to visit recreation sites with
higher levels of environmental quality (e.g., cleaner water in the lake,
more fish to catch, a better view from a mountain with low air
pollution). In travel cost analysis, researchers gather data on the
environmental features of a set of recreation sites and the choices
people make about visiting those sites—which they choose to visit,
and how often—and apply statistical analysis to those data to estimate
WTP for improved quality of natural amenities.
One of the greatest strengths of revealed preference valuation methods is
that they use information about real behavior rather than hypothetical
choices. These approaches also yield estimates of WTP that are often more
complete than the results of direct market measure studies.
Revealed preference studies do, however, have weaknesses and limitations.
First, they only give good estimates of WTP for environmental goods if
people have full and accurate information about environmental quality and
associated risks. For example, hedonic estimates of WTP to avoid living
with polluted air will be biased downward if people in a city do not know
how air pollution varies among neighborhoods. Second, some revealed
preference approaches are only valid if the relevant markets (labor markets
for a wage study, housing markets for a hedonic price study) are not
plagued by market power and transaction costs that prevent efficient
equilibria from being reached. For example, if workers find it too daunting
and costly to move from one region to another, then coal miners may fail to
earn the wage premium that would be associated with such a risky job in
the absence of relocation hurdles. Third, revealed preference approaches
cannot be used to estimate values for levels of environmental quality that
are not observed in real-world data. If all the lakes in a region are terribly
polluted, we cannot use a travel cost study of lake site choice to identify
WTP for very clean lakes. Fourth, revealed preference methods can capture
only use values, not non-use values.
The limitations of revealed preference valuation tools motivated
environmental and natural resource economists to develop valuation
methods that do not require analysts to be able to observe real-world
behavior related to the amenity being valued. These stated preference
methods are now highly refined, but the essential idea is simple. These
studies design a survey that presents people with information about
hypothetical scenarios involving an environmental good, gather data on
their responses to questions about how much they would pay for something
or whether they would choose one scenario over another, and then analyze
the data to estimate WTP for the good or WTA compensation for
elimination or degradation of the good.
¢ Contingent valuation: The methodology called contingent valuation
(or CV) gained prominent attention when it was used by economists to
estimate the damage done to society by the oil spilled by Exxon’s
Valdez oil tanker in Prince William Sound in 1989 (Carson et al.,
2003). A CV survey gives a clear description of a single environmental
amenity to be valued, such as a wetland restoration, whale populations,
or improved water quality in a local lake. The description includes
details about how the amenity would be created, and how the survey
respondent would pay any money they claim to be willing to pay in
support of the amenity. Respondents are then asked a question to elicit
their WTP. This value elicitation question can be open ended (“How
much would you be willing to pay in taxes to increase whale
populations?) or closed ended (“Would you be willing to pay $30 to
increase whale populations?). The resulting data set is analyzed to find
the average WTP of people in the sample population.
¢ Conjoint analysis: Conjoint analysis is also referred to as choice
experiment survey analysis. It was developed first by analysts in
business marketing and psychology, and only later adopted by
economists for environmental valuation. The main difference between
conjoint analysis and CV is that CV elicits WTP for an environmental
amenity with a single fixed bundle of features, or attributes. Conjoint
analysis estimates separate values for each of a set of attributes of a
composite environmental amenity. For example, grasslands can vary in
bird species diversity, wildflower coverage, and distance from human
population centers. A conjoint analysis of grassland ecosystems would
construct a set of hypothetical grasslands with varied combinations of
attributes (including the cost to the respondent of a chosen grassland).
The survey would present respondents with several choice questions;
in each choice, the respondent would be asked to pick which of several
hypothetical grasslands they would prefer. The resulting data would be
analyzed to find how each attribute affects the likelihood that one
grassland is preferred over another. This would yield estimates of
marginal values for each attribute; those values could then be used to
find WTP for composite grasslands with many different combinations
of features.
Both CV and conjoint analysis methods can be designed to estimate WTP
for improvement or WTA degradation depending on which context is most
appropriate for the problem at hand. These stated preference methods have
two main strengths. First, they can capture non-use values. Second, their
hypothetical nature allows analysts to estimate WTP for improvements out
of the range of current experience (or WTA for degradation we have
fortunately not yet experienced).
However, stated preferences approaches do have weaknesses and
limitations. For example, many economists are uncomfortable using value
estimates derived from hypothetical choices, worrying whether consumers
would make the same choices regarding payment for public environmental
goods if the payments were real. Scholars also worry about whether people
give responses to stated preference surveys that are deliberately skewed
from their true WTP. Understatements of value could arise to protest a
government policy (“Why should I have to pay to clean up the environment
when someone else made it dirty in the first place?”’) or out of a desire to
free ride. Finally, the hypothetical nature of stated preference surveys can
mean that some respondents are not familiar with the thing being valued,
and thus may have trouble giving meaningful responses to the questions.
Stated preference surveys must be designed to give respondents enough
information without biasing their responses.
References
Carson, R. T., Mitchell, R. C., Hanemann, M., Kopp, R. J., Presser, S., and
Ruud, P. A. (2003). Contingent valuation and lost passive use: Damages
from the Exxon Valdez oil spill. Environmental and Resource Economics,
25(3), 257-286. DOI: 10.1023/A:1024486702104.
Costanza, R., d'Arge, R., de Groot, R., Farber, S., Grasso, M., Hannon, B.,
Limburg, K., Naeem, S., O'Neill, R. V., Paruelo, J., Raskin, R. G., Sutton,
P., & van den Bel, M. (1997). The value of the world's ecosystem services
and natural capital. Nature, 387, 253-260. doi:10.1038/387253a0
Review Questions
Exercise:
Problem:
Why might it be useful to estimate dollar values for features of the
environment?
Exercise:
Problem:
What are the three types of valuation tools? List at least one strength
and one weakness of each.
Glossary
avoided cost
A type of direct method that equates the value of an environmental
improvement with a cost that can then be avoided.
benefit transfer
A method for estimating the value of a natural amenity by applying
estimates from a complex study of a slightly different (but similar)
amenity to the case at hand.
conjoint analysis
A stated preference valuation tool that allows an analyst to estimate the
marginal values of multiple attributes of an environmental good.
contingent valuation
A stated preference valuation tool that describes a single
environmental good and elicits survey responses from which the
analyst can estimate people’s value for that good.
direct methods
Valuation tools that use data on actual market transactions to estimate
the value of a change in the environment.
ecosystem services
Resources and processes through which the environment gives benefits
to humanity.
hedonic price analysis
A revealed preference tool that uses data on house prices and
characteristics to estimate the value of features of the environment that
vary among houses.
hedonic wage analysis
A revealed preference tool that uses data on wages and risk of death by
job type estimate willingness to pay to reduce the risk of death.
non-use values
Values people have for nature that do not stem from direct interaction.
revealed preference
Valuation tools that use behaviors such as job choice, housing choice,
and recreational site choice to reveal information about the values
people have for features of the environment.
stated preference
Valuation tools that use survey responses to hypothetical questions
rather than data on actual choices.
travel cost analysis
A revealed preference tool that estimates the values of natural resource
amenities by analyzing data on recreational site characteristics and
people’s visitation patterns and travel costs.
use values
Benefits associated with direct interaction with nature and the
environment.
valuation
The process of estimating a dollar value for an amenity or a
disamentity.
value of a statistical life
A statistical concept that can be used as the value of reducing the
number of deaths in a population by one.
willingness to accept
The amount of money you would have to pay someone to compensate
them for a deleterious change.
willingness to pay
The amount of money someone is willing to pay for something good.
Evaluating Projects and Policies
In this module, the following topics are covered: 1) the challenges of policy
evaluation when costs and benefits accrue over time, 2) features of cost-
benefit analysis, and 3) criteria for policy evaluation.
Learning Objectives
After reading this module, students should be able to
e know five important features of how economists think about costs
e understand why discounting is both important and controversial, and
be able to calculate the net present value of a project or policy
e know what cost-benefit analysis is, and be aware of some of its
limitations
e think about four criteria for evaluating a project that are not captured
in a basic cost-benefit analysis
Introduction
Environmental valuation methods help analysts to evaluate the benefits
society would gain from policies or cleanup and restoration projects that
improve environmental quality or better steward our natural resources.
Another set of tools can yield information about the costs of such actions (a
brief description is below). But even if we have plausible estimates of the
costs and benefits of something, more work needs to be done to put all that
information together and make some rational choices about public policy
and investments. This module discusses the challenges of policy evaluation
when costs and benefits accrue over time, outlines the main features of cost-
benefit analysis, and presents several other criteria for policy evaluation.
Net Present Value, Discounting, and Cost-benefit Analysis
Cost estimation has not generated the same amount of scholarly research as
benefit valuation because the process of estimating the costs of
environmental improvement is usually more straightforward than the
process of estimating the benefits. Economists do think differently about
costs than engineers or other physical scientists, and several key insights
about the economics of cost evaluation are important for policy analysis.
Viewed through an inverse lens, all these ideas are important for benefit
estimation as well.
Opportunity Cost
Not all costs involve actual outlays of money. An opportunity cost is the
foregone benefit of something that we choose (or are forced) not to do. The
opportunity cost of a year of graduate school is the money you could have
made if you had instead gotten a full-time job right after college.
Endangered species protection has many opportunity costs: timber in old-
growth forests can’t be cut and sold; critical habitat in urban areas can’t be
developed into housing and sold to people who want to live in the area.
Opportunity costs do not appear on firms’ or governments’ accounting
sheets and are thus often overlooked in estimates of the costs of a policy.
Studies of U.S. expenditures on endangered species’ recoveries have used
only information about costs like direct government expenditures because
opportunity costs are so challenging to measure (e.g. Dawson and Shogren,
2001).
A Redwood Forest in California
Forests can’t both be cut down and
preserved for habitat. The dollar
cost of lumber is straightforward to
quantify, but it is more difficult to
quantify the value of ecosystems.
Cutting down the forest therefore
has an opportunity cost that is hard
to measure, and this can bias
people and governments towards
resource extraction. Source: Photo
by Michael Barera
Transfers Are Not Costs
Cost totals should only include real changes in behavior or resource use,
and not transfers of money from one party to another. For example, imagine
a program in which a wastewater treatment plant can pay a farmer for the
cost of taking land out of production and installing a wetland on the land
that will soak up nutrients that would otherwise flow into a local river. The
cost of those nutrient reductions is the cost of installing the wetland and the
opportunity cost of the foregone farming activity. If payments for multiple
services are permitted, the farmer might also be able to get paid by a
conservation group for the wildlife benefit associated with the new wetland.
However, that additional payment to the farmer is a pure transfer. The social
cost of the wetland has not gone up just because the farmer was paid more
for it.
Use the Correct Counterfactual
Many cursory analyses of the costs of a policy find the difference between
the cost of something before and after the policy was put in place and claim
that any increase was caused by the policy. For example, the U.S.
government put temporary restrictions on offshore oil drilling after the
Deepwater Horizon explosion and oil spill to consider new environmental
regulations on such drilling. After those restrictions were put in place, the
price of crude oil in the U.S. went up. A sloppy analysis would attribute all
the costs of that price increase to the drilling restrictions. However, during
the same period of 2010, the U.S. economy was beginning to pull out of a
very deep recession; this caused increased manufacturing activity and
consumer driving, and thus an increased call for fossil-fuel energy.
Therefore, some of the increase in oil prices might have been driven by the
increased demand for oil. A careful analysis would compare the price of oil
with the restrictions in place to what the price of oil would have been
during the same time period if the restrictions had not been implemented—
that hypothetical scenario is the true counterfactual.
Additionality
A careful analysis of the costs of a program includes only costs that are
additional, that is, new additions to costs that would have existed even in
the absence of the program. For example, current regulations require
developers to use temporary controls while constructing a new building to
prevent large amounts of sediment from being washed into local rivers and
lakes. Suppose EPA wants to estimate the costs of a new regulation that
further requires new development to be designed such that stormwater
doesn’t run off the site after the building is finished. A proper analysis
would not include the costs of the temporary stormwater controls in the
estimate of the cost of the new regulation, because those temporary controls
would be required even in the absence of the new regulation (Braden and
Ando,_2011). The concept of additionality has been made famous in the
context of benefit estimation by a debate over whether programs that pay
landowners not to deforest their lands have benefits that are additional;
some of those lands might not have been deforested even without the
payments, or the landowners may receive conservation payments from
multiple sources for the same activity.
Control for Associated Market Changes
A careful cost analysis must pay attention to market changes associated
with cost increases. To illustrate, suppose the government is thinking of
passing a ban on agricultural use of methyl bromide. This ozone-depleting
chemical is widely used as an agricultural fumigant, and is particularly
important in strawberry production and shipping. A ban on methyl bromide
might, therefore, increase the marginal cost of producing strawberries. A
simple approach to estimating the cost of the proposed methyl bromide ban
would be to find out how many strawberries were sold before the ban and
calculate the increase in the total cost of producing that many strawberries.
However, the increase in production costs will drive up the price of
strawberries and lower the number of strawberries sold in the marketplace.
There is a cost to society with two parts: (a) deadweight loss associated
with the net benefits of the strawberries not sold, and (b) the increased cost
of producing the strawberries that still are sold. That total social cost is
lower, however, than the estimate yielded by the simple approach outlined
above because the simple approach includes increased production costs for
strawberries that are not sold. An accurate cost estimate must take into
account market changes.
The concept of net benefits was introduced above; in the context of policy
or project evaluation, net benefits are, quite simply, the difference between
the benefits and the costs of a policy in a given year. However,
environmental policies typically have benefits and costs that play out over a
long period of time, and those flows are often not the same in every year.
For example, wetland restoration in agricultural areas has a large fixed cost
at the beginning of the project when the wetland is constructed and planted.
Every year after that there is an opportunity cost associated with foregone
farm income from the land in the wetland, but that annual cost is probably
lower than the fixed construction cost. The wetland will yield benefits to
society by preventing the flow of some nitrogen and phosphorus into nearby
streams and by providing habitat for waterfowl and other animals.
However, the wildlife benefits will be low in the early years, increasing
over time as the restored wetland vegetation grows and matures. It is not
too difficult to calculate the net benefits of the restoration project in each
year, but a different methodology is needed to evaluate the net benefits of
the project over its lifetime.
Some analysts simply add up all the costs and benefits for the years that
they accrue. However, that approach assumes implicitly that we are
indifferent between costs and benefits we experience now and those we
experience in the future. That assumption is invalid for two reasons. First,
empirical evidence has shown that humans are impatient and prefer benefits
today over benefits tomorrow. One need only ask a child whether they want
to eat a candy bar today or next week in order to see that behavior at work.
Second, the world is full of investment opportunities (both financial and
physical). Money today is worth more than money tomorrow because we
could invest the money today and earn a rate of return. Thus, if there is a
cost to environmental cleanup, we would rather pay those costs in the future
than pay them now.
Economists have developed a tool for comparing net benefits at different
points in time called discounting. Discounting converts a quantity of
money received at some point in the future into a quantity that can be
directly compared to money received today, controlling for the time
preference described above. To do this, an analyst assumes a discount rate r,
where r ranges commonly between zero and ten percent depending on the
application. If we denote the net benefits t years from now as V¢(in the
current year, t=0), then we say the present discounted value of V¢t is
PDV(V,) = aay Figure 6.4.2 shows how the present value of $10,000
declines with time, and how the rate of the decrease varies with the choice
of discount rate r. If a project has costs and benefits every year for T years,
then the net present value of the entire project is given by
fu Vi
NPV = Yio Ga
$10,000
oon <
Year
The Impact of a Discount Rate on Present Value Estimates Source:
A particular cost or benefit is worth less in present value terms the farther
into the future it accrues and the higher the value of the discount rate. These
fundamental features of discounting create controversy over the use of
discounting because they make projects to deal with long-term
environmental problems seem unappealing. The most pressing example of
such controversy swirls around analysis of climate-change policy. Climate-
change mitigation policies typically incur immediate economic costs (e.g.
switching from fossil fuels to more expensive forms of energy) to prevent
environmental damages from climate change several decades in the future.
Discounting lowers the present value of the future improved environment
while leaving the present value of current costs largely unchanged.
Cost-benefit analysis is just that: analysis of the costs and benefits of a
proposed policy or project. To carry out a cost-benefit analysis, one
carefully specifies the change to be evaluated, measures the costs and
benefits of that change for all years that will be affected by the change,
finds the totals of the presented discounted values of those costs and
benefits, and compares them. Some studies look at the difference between
the benefits and the costs (the net present value), while others look at the
ratio of benefits to costs. A “good” project is one with a net present value
greater than zero and a benefit/cost ratio greater than one.
The result of a cost-benefit analysis depends on a large number of choices
and assumptions. What discount rate is assumed? What is the status quo
counterfactual against which the policy is evaluated? How are the physical
effects of the policy being modeled? Which costs and benefits are included
in the analysis—are non-use benefits left out? Good cost-benefit analyses
should make all their assumptions clear and transparent. Even better
practice explores whether the results of the analysis are sensitive to
assumptions about things like the discount rate (a practice called sensitivity
analysis). Scandal erupted in 2000 when a whistle-blower revealed that the
Army Corps of Engineers was pressuring its staff to alter assumptions to
make sure a cost-benefit analysis yielded a particular result (EDV&CBN,
2000). Transparency and sensitivity analysis can help to prevent such
abuses.
Efficiency, Cost Effectiveness, Innovation, and Equity
Cost-benefit analysis gives us a rough sense of whether or not a project is a
good idea. However, it has many limitations. Here we discuss several other
measures of whether a project is desirable. Economists use all these criteria
and more when evaluating whether a policy is the right approach for
solving a problem with externalities, public goods, and common-pool
resources.
Efficiency
A policy is efficient if it maximizes the net benefits society could get from
an action of that kind. Many projects and policies can pass a cost-benefit
test but still not be efficient. Several levels of carbon dioxide emission
reduction, for example, could have benefits exceeding costs, but only one
will have the largest difference between benefits and costs possible. Such
efficiency will occur when the marginal benefits of the policy are equal to
its marginal costs. Sometimes a cost-benefit analysis will try to estimate the
total costs and benefits for several policies with different degrees of
stringency to try to see if one is better than the others. However, only
information about the marginal benefit and marginal cost curves will ensure
that the analyst has found the efficient policy. Unfortunately, such
information is often very hard to find or estimate.
Cost Effectiveness
As we Saw in the Module Environmental Valuation, it can be particularly
difficult to estimate the benefits of environmental policy, and benefit
estimates are necessary for finding efficient policies. Sometimes policy
goals are just set through political processes—reducing sulfur dioxide
emissions by 10 million tons below 1980 levels in the Clean Air Act acid
rain provisions, cutting carbon dioxide emissions by 5% from 1990 levels
in the Kyoto protocol—without being able to know whether those targets
are efficient. However, we can still evaluate whether a policy will be cost
effective and achieve its goal in the least expensive way possible. For
example, for total pollution reduction to be distributed cost-effectively
between all the sources that contribute pollution to an area (e.g. a lake or an
urban airshed), it must be true that each of the sources is cleaning up such
that they all face the same marginal costs of further abatement. If one
source had a high marginal cost and another’s marginal cost was very low,
total cost could be reduced by switching some of the cleanup from the first
source to the second.
Incentives to Innovate:
At any one point in time, the cost of pollution control or resource recovery
depends on the current state of technology and knowledge. For example, the
cost of reducing carbon dioxide emissions from fossil fuels depends in part
on how expensive solar and wind power are, and the cost of wetland
restoration depends on how quickly ecologists are able to get new wetland
plants to be established. Everyone in society benefits if those technologies
improve and the marginal cost of any given level of environmental
stewardship declines. Thus, economists think a lot about which kinds of
policies do the best job of giving people incentives to develop cheaper ways
to clean and steward the environment.
Fairness
A project can have very high aggregate net benefits, but distribute the costs
and benefits very unevenly within society. We may have both ethical and
practical reasons not to want a policy that is highly unfair. Some people
have strong moral or philosophical preferences for policies that are
equitable. In addition, if the costs of a policy are borne disproportionately
by a single group of people or firms, that group is likely to fight against it in
the political process. Simple cost-benefit analyses do not speak to issues of
equity. However, it is common for policy analyses to break total costs and
benefits down among subgroups to see if uneven patterns exist in their
distribution. Studies can break down policy effects by income category to
see if a policy helps or hurts people disproportionately depending on
whether they are wealthy or poor. Other analyses carry out regional
analyses of policy effects. . For example, climate-change mitigation policy
increases costs disproportionately for poor households because of patterns
in energy consumption across income groups. Furthermore, the benefits and
costs of such policy are not uniform across space in the U.S. The benefits of
reducing the severity of climate change will accrue largely to those areas
that would be hurt most by global warming (coastal states hit by sea level
rise and more hurricanes, Western states hit by severe water shortages)
while the costs will fall most heavily on regions of the country with
economies dependent on sales of oil and coal.
Some of our evaluative criteria are closely related to each other; a policy
cannot be efficient if it is not cost-effective. However, other criteria have
nothing to do with each other; a policy can be efficient but not equitable,
and vice versa. Cost-benefit analyses provide crude litmus tests—we surely
do not want to adopt policies that have costs exceeding their benefits.
However, good policy development and evaluation considers a broader
array of criteria.
Review Questions
Exercise:
Problem:
What are some common mistakes people make in evaluating the costs
of a policy or project, and what should you do to avoid them?
Exercise:
Problem:
What is discounting, and how do we use it in calculating the costs and
the benefits of a project that has effects over a long period of time?
Exercise:
Problem: Why is discounting controversial?
Exercise:
Problem:
How does cost-benefit analysis complement some of the other
measures people use to evaluate a policy or project?
References
Braden, J. B. & A. W. Ando. 2011. Economic costs, benefits, and
achievability of low-impact development based stormwater regulations, in
Economic Incentives for Stormwater Control, Hale W. Thurston, ed., Taylor
& Francis, Boca Raton, FL.
Carson, R. T., Mitchell, R. C., Hanemann, M., Kopp, R. J., Presser, S., and
Ruud, P. A. (2003).Contingent valuation and lost passive use: Damages
from the Exxon Valdez oil spill. Environmental and Resource Economics,
25(3), 257-286. DOI: 10.1023/A:1024486702104.
Dawson, D. & Shogren, J. F. (2001). An update on priorities and
expenditures under the Endangered Species Act. Land Economics, 77(4),
527-032.
EDV&CBN (2000). Environmental groups protest alteration of U.S. Army
Corps cost benefit analysis. Environmental Damage Valuation and Cost
Benefit News, 7(4), 1-3.
http://www.costbenefitanalysis.org/newsletters/nwsOO0apr.pdf .
Glossary
additionality
The extent to which a new action (policy, project etc.) adds to the
benefits or costs associated with existing conditions.
cost-benefit analysis
Evaluation of how the overall benefits of a project compare to its costs.
cost effectiveness
The extent to which an outcome is achieved at the lowest cost possible.
counterfactual
The scenario against which a different scenario should be compared; in
policy analysis, the way the world would have been in the absence of
the policy.
discounting
The process of converting future values (costs or benefits) into an
equivalent amount of money received today; controls for human time
preference.
net present value
The present discounted value of a stream of net benefits.
opportunity cost
The cost of foregoing the next best choice when making a decision.
present discounted value
The value of something in present-day (rather than future) terms.
sensitivity analysis
Evaluation of how sensitive the results of an analysis are to changes in
assumptions used in the analysis.
Solutions: Property Rights, Regulations, and Incentive Policies
In this module, the following topics will be covered: 1) defined property
rights, 2) types of command and control regulations, and 3) incentive
policies.
Learning Objectives
After reading this module, students should be able to
¢ know why having clearly defined property rights might improve
environmental outcomes and be aware of the limitations of that
approach
e define several different types of command and control regulations, and
understand their comparative advantages
e know what incentive policies (taxes and tradable permits) are, what
they do, and what their strengths and weaknesses are
Introduction
Governments have implemented many policies to solve problems with
environmental quality and natural resource depletion. Every policy is
unique and deserves detailed individual analysis in the policymaking
process—the devil is always in the details. However, economists have
developed a taxonomy of policy types. This taxonomy helps us to
understand general principles about how policies of different types are
likely to perform and under which circumstances they are likely to work
best. Policies are broadly characterized as either command-and-control or
incentive policies. Command and control includes several types of
standards. Incentive policies include taxes, tradable permits, and liability.
Property Rights
In 1960, Ronald Coase wrote the pioneering article "The Problem of Social
Cost" in which he put forth ideas about externalities that have come to be
known as the Coase theorem (Coase, 1960). The basic idea of the Coase
theorem is that if property rights over a resource are well specified, and if
the parties with an interest in that resource can bargain freely, then the
parties will negotiate an outcome that is efficient regardless of who has the
rights over the resource. The initial allocation of rights will not affect the
efficiency of the outcome, but it will affect the distribution of wealth
between the parties because the party with the property rights can extract
payment from the other parties as part of the agreement.
To bring this abstract idea to life, we will draw on the classic example
employed by generations of economists to think about the Coase theorem.
Suppose a farmer and a rancher live next door to each other. There is land
between them on which the farmer wants to plant crops, but the rancher's
cows keep eating the crops. The farmer would like to have no cows on the
land, and the rancher would like the farmer to stop planting crops so the
cows could eat as much grass as they like. The efficient outcome is where
the marginal benefit of a cow to the rancher is just equal to the marginal
cost to the farmer of that cow's grazing. If the farmer is given property
rights over the land, the rancher will have an incentive to pay the farmer to
allow the efficient number of cows rather than zero; if the rancher has the
rights, then the farmer will have to pay the rancher to limit the herd to just
the efficient size. Either way they have incentives to negotiate to the
efficient outcome because otherwise both of them could be made better off.
The Coase theorem is invoked by some scholars and policy analysts to
argue that government policy is not needed to correct problems of
externalities; all you need is property rights, and private negotiations will
take care of the rest. However, Coase himself recognized in his writing that
often the real world does not have the frictionless perfect negotiation on
which the conclusions of the theorem rest. For example, there are
transaction costs in bargaining, and those transaction costs can be
prohibitively large when many people are involved, as in the case of air
pollution from a factory. Furthermore, perfect bargaining requires perfect
information. People often are unaware of the threats posed to their health by
air and water pollution, and thus do not know what kind of bargaining
would actually be in their own best interests.
Despite these limitations, there is a move afoot to use property right
development to effect environmental improvement and improve natural
resource stewardship, particularly in developing countries. In parts of
Africa, new systems have given villages property rights over wildlife on
their lands, yielding stronger incentives to manage wildlife well and
demonstrably increasing wildlife populations. In South America, land-
tenure reform is promoted as a way to reduce deforestation.
Command and Control Regulations
Most environmental policy in the United States is much more rigid and
controlling than property-rights reform. Our policies for things like clean air
and water, toxic waste cleanup, and endangered species protection have
largely been composed of rigid rules and regulations. Under such policies,
people are given strict and specific rules about things they must or must not
do regarding some facet of pollution control or natural resource use, and
then a government agency enforces the rules. Here we discuss and explore
examples of a few kinds of such "command-and-control" regulations.
Ambient Standard
Some policies have targets for the quality of some element of the
environment that results from human behavior and natural processes. An
ambient standard establishes a level of environmental quality that must be
met. The Clean Air Act directs the U.S. Environmental Protection Agency
(EPA) to establish National Ambient Air Quality Standards (NAAQSs) for
a range of air pollutants such as ozone and fine particles. The Clean Water
Act directs state offices of the EPA to set ambient water quality standards
for rivers and streams in their boundaries. In practice, however, such
standards are binding only on state regulators. State EPA offices are
responsible for developing plans to ensure that air and surface water bodies
meet these ambient quality standards, but they cannot do the clean up on
their own. They need to use a different set of tools to induce private agents
to actually reduce or clean up pollution such that the ambient standards can
be met.
Some ambient standards (such as the NAAQSs) have provoked criticism
from economists for being uniform across space. Every county in the
country has to meet the same air quality goals, even though the efficient
levels of air quality might vary from one county to the next with variation
in the marginal benefits and marginal costs of cleaning the air. However,
uniform ambient standards grant all people in the U.S. the same access to
clean air—a goal that has powerful appeal on the grounds of equity.
Individual Standards
First, we discuss a kind of policy applied to individual people or companies
called a technology_standard. Pollution and resource degradation result
from a combination of human activity and the characteristics of the
technology that humans employ in that activity. Behavior can be difficult to
monitor and control. Hence, lawmakers have often drafted rules to control
our tools rather than our behaviors. For example, automakers are required to
install catalytic converters on new automobiles so that cars have lower
pollution rates, and people in some parts of the country must use low-flow
showerheads and water-efficient toilets to try to reduce water usage.
Technology standards have the great advantage of being easy to monitor
and enforce; it is easy for a regulator to check what pollution controls are in
the design of a car. Under some circumstances technology standards can
reduce pollution and the rate of natural resource destruction, but they have
several serious limitations. First, they provide no incentives for people to
alter elements of their behavior other than technology choice. Cars may
have to have catalytic converters to reduce emissions per mile, but people
are given no reason to reduce the number of miles they drive. Indeed, these
policies can sometimes have perverse effects on behavior. Early generations
of water-efficient toilets performed very poorly; they used fewer gallons of
water per flush, but people found themselves flushing multiple times in
order to get waste down the pipes. Thus, these standards are neither always
efficient nor cost effective. Second, technology standards are the worst
policy in the toolkit for promoting technological innovation. Firms are
actively forbidden from using any technology other than the one specified
in the standards. Automakers might think of a better and cheaper way to
reduce air pollution from cars, but the standard says they have to use
catalytic converters.
A second type of policy applied to individual agents is called a
performance standard. Performance standards set strict limits on an
outcome of human activity. For example, in order to meet the NAAQSs,
state EPA offices set emission standards for air pollution sources in their
states. Those standards limit the amount of pollution a factory or power
plant can release into the air, though each source can control its pollution in
any way it sees fit. The limits on pollution are the same for all sources of a
given type (e.g., power plant, cement factory, etc.). Performance standards
are also used in natural resource regulation. For example, because
stormwater runoff causes flooding and harms aquatic habitat, the city of
Chicago requires all new development to be designed handle the first inch
of rainfall in a storm onsite before runoff begins.
To enforce a performance standard the regulator must be able to observe the
outcome of the agents’ activities (e.g. measure the pollution, estimate the
runoff). If that is possible, these policies have some advantages over
technology standards. Performance standards do give people and firms
some incentive to innovate and find cheaper ways to reduce pollution
because they are free to use any technology they like to meet the stated
requirements. Performance standards are also more efficient because they
give people and firms incentives to change multiple things about their
activity to reduce the total cost of pollution abatement; a power plant can
reduce sulfur dioxide emissions by some combination of installing scrubber
technology, switching to low-sulfur coal, and reducing total energy
generation.
Performance standards also have some drawbacks and limitations, however.
It is difficult for a regulator to figure out the cost effective allocation of total
pollution reduction between sources and then set different performance
standards for each source to reach that cost effective allocation. Hence,
performance standards tend to be uniform across individual pollution
sources, and so pollution reduction is not done in the cheapest way possible
for the industry and society overall. This problem is particularly severe
where there is great variation among sources in their abatement costs, and
thus the cost-effective allocation of cleanup among sources is far from
uniform.
Incentive Policies
Other approaches to environmental policy give firms and individuals
incentives to change their behavior rather than mandating specific changes.
These incentive policies try to make use of market forces for what they do
best—allocating resources cost-effectively within an economy—while
correcting the market failures associated with externalities, public goods,
and common pool resources.
Tax/Subsidy
Environmental taxes are based on a simple premise: if someone is not
bearing the full social costs of their actions, then we should charge them an
externality tax per unit of harmful activity (e.g. ton of pollution, gallon of
stormwater runoff) that is equal to the marginal cost that is not borne by the
individual. In this way, that person must internalize the externality, and will
have the incentive to choose a level of activity that is socially optimal.
Thus, if we think the social marginal cost of ton of carbon dioxide (because
of its contribution to climate change) is $20, then we could charge a tax of
$20 per ton of carbon dioxide emitted. The easiest way to do this would be
to have a tax on fossil fuels according to the amount of carbon dioxide that
will be emitted when they are burned.
If a price is placed on carbon dioxide, all agents would have an incentive to
reduce their carbon dioxide emissions to the point where the cost to them of
reducing one more unit (their marginal abatement cost) is equal to the per
unit tax. Therefore, several good things happen. All carbon dioxide sources
are abating to the same marginal abatement cost, so the total abatement is
accomplished in the most cost-effective way possible. Furthermore, total
emissions in the economy overall will go down to the socially efficient
level. Firms and individuals have very broad incentives to change things to
reduce carbon dioxide emissions—reduce output and consumption, increase
energy efficiency, switch to low carbon fuels—and strong incentives to
figure out how to innovate so those changes are less costly. Finally, the
government could use the revenue it collects from the tax to correct any
inequities in the distribution of the program's cost among people in the
economy or to reduce other taxes on things like income.
While taxes on externality-generating activities have many good features,
they also have several drawbacks and limitations. First, while an externality
tax can yield the efficient outcome (where costs and benefits are balanced
for the economy as a whole), that only happens if policy makers know
enough about the value of the externality to set the tax at the right level. If
the tax is too low, we will have too much of the harmful activity; if the tax
is too high, the activity will be excessively suppressed.
Second, even if we are able to design a perfect externality tax in theory,
such a policy can be difficult to enforce. The enforcement agency needs to
be able to measure the total quantity of the thing being taxed. In some cases
that is easy—in the case of carbon dioxide for example, the particular fixed
link between carbon dioxide emissions and quantities of fossil fuels burned
means that through the easy task of measuring fossil fuel consumption we
can measure the vast majority of carbon dioxide emissions. However, many
externality-causing activities or materials are difficult to measure in total.
Nitrogen pollution flows into streams as a result of fertilizer applications on
suburban lawns, but it is impossible actually to measure the total flow of
nitrogen from a single lawn over the course of a year so that one could tax
the homeowner for that flow.
Third, externality taxes face strong political opposition from companies and
individuals who don't want to pay the tax. Even if the government uses the
tax revenues to do good things or to reduce other tax rates, the group that
disproportionately pays the tax has an incentive to lobby heavily against
such a policy. This phenomenon is at least partly responsible for the fact
that there are no examples of pollution taxes in the U.S. Instead, U.S. policy
makers have implemented mirror-image subsidy policies, giving subsidies
for activities that reduce negative externalities rather than taxing activities
that cause those externalities. Environmental policy in the case of U.S.
agriculture is a prime example of this, with programs that pay farmers to
take lands out of production or to adopt environmentally friendly farming
practices. A subsidy is equivalent to the mirror-image tax in most ways.
However, a subsidy tends to make the relevant industry more profitable (in
contrast to a tax, which reduces profits), which in turn can stimulate greater
output and have a slight perverse effect on total pollution or environmental
degradation; degradation per unit output might go down, but total output
goes up.
Tradable Permits
Another major type of incentive policy is a tradable permits scheme.
Tradable permits are actually very similar to externality taxes, but they can
have important differences. These policies are colloquially known as "cap
and trade". If we know the efficient amount of the activity to have (e.g.,
number of tons of pollution, amount of timber to be logged) the policy
maker can set a cap on the total amount of the activity equal to the efficient
amount. Permits are created such that each permit grants the holder
permission for one unit of the activity. The government distributes these
permits to the affected individuals or firms, and gives them permission to
sell (trade) them to one another. In order to be in compliance with the policy
(and avoid punishment, such as heavy fines) all agents must hold enough
permits to cover their total activity for the time period. The government
doesn't set a price for the activity in question, but the permit market yields a
price for the permits that gives all the market participants strong incentives
to reduce their externality-generating activities, to make cost-effective
trades with other participants, and to innovate to find cheaper ways to be in
compliance. Tradable permit policies are similar to externality taxes in
terms of efficiency, cost-effectiveness, and incentives to innovate.
Tradable permit policies have been used in several environmental and
natural resource policies. The U.S. used tradable permits (where the annual
cap declined to zero over a fixed number of years) in two separate policy
applications to reduce the total cost to society of (a) phasing out the use of
lead in gasoline and (b) eliminating production of ozone-depleting
chlorofluorocarbons. The Clean Air Act amendments of 1990 put in place a
nationwide tradable permit program for emissions of acid-rain precursor
sulfur dioxide from electric power plants. The European Union used a
tradable permit market as part of its policy to reduce carbon dioxide
emissions under the Kyoto protocol. Individual tradable quotas for fish in
fisheries of Alaska and New Zealand have been used to rationalize fishing
activity and keep total catches down to efficient and sustainable levels (see
Case Study: Marine Fisheries).
Tradable permits have been adopted more widely than externality taxes.
Two factors may contribute to that difference. First, tradable permit policies
can have different distributional effects from taxes depending on how the
permits are given out. If the government auctions the permits to participants
in a competitive marketplace, then the tradable permit scheme is the same
as the tax; the industry pays the government an amount equal to the number
of permits multiplied by the permit price. However, policy makers more
commonly design policies where the permits are initially given for free to
participants in the market, and then participants sell the permits to each
other. This eliminates the transfer of wealth from the regulated sector (the
electric utilities, the fishing boats, etc.) to the government, a feature that has
been popular with industry. Second, taxes and tradable permits behave
differently in the face of uncertainty. A tax policy fixes the marginal cost to
the industry, but might yield more or less of the harmful activity than
expected if market conditions fluctuate. A cap and trade program fixes the
total amount of the harmful activity, but can yield costs to industry that are
wildly variable. Environmentalists have liked the outcome certainty of
tradable permits.
Liability
A third type of environmental policy was not designed by economists, but
still functions to give agents incentives to take efficient actions to reduce
environmental degradation: liability. Liability provisions can make people
or firms pay for the damages caused by their actions. If the expected
payment is equal to the total externality cost, then liability makes the agent
internalize the externality and take efficient precautions to avoid harming
the environment.
Two kinds of liability exist in the U.S.: statutory and common law.
Common law derives from a long tradition of legal history in the U.S.—
people have sued companies for damages from pollution under tort law
under doctrines such as nuisance, negligence, or trespass. This approach has
been highly problematic for a number of reasons. For example, tort law
places a high burden of proof on the plaintiff to show that damages resulted
directly from actions taken by the defendant. Plaintiffs have often struggled
with that burden because pollution problems are often caused by many
sources, and the harm caused by pollution can display large lags in space
and time. If the defendant expects with high probability not to be held
responsible by the courts, then liability does not function effectively to
make agents internalize the externality costs of their actions.
Frustration with common law has led to several strong statutory liability
laws in the U.S. which make explicit provisions for holding firms liable for
damages from pollution with much more manageable burdens of proof. The
Oil Pollution Act of 1990 holds companies like Exxon and British
Petroleum strictly liable for the damages caused by oil spills from accidents
such as the Valdez grounding in Prince William Sound or the Deepwater
Horizon explosion in the Gulf of Mexico. Under a rule of strict liability, a
party is liable for harm if the harm occurred as a result of their actions
regardless of the presence (or absence) of negligence or intent. The
Comprehensive Environmental Response, Compensation, and Liability Act
(CERCLA, or "Superfund") holds companies strictly liable for damages
from toxic waste "Superfund" sites.
These laws have surely increased the extent to which oil and chemical
companies take precautions to avoid spills and other releases of hazardous
materials into the environment. However, enforcement of these provisions
is very costly. The legal proceedings for a big case like Deepwater Horizon
entail court, lawyer, and expert witness activity (and high fees) for many
years. The transaction costs are so burdensome to society that liability may
not be a viable approach for all environmental problems.
Review questions
Exercise:
Problem:
What are some of the strengths and weaknesses of command and
control regulation? When would these be the best policy tool to use?
Exercise:
Problem:
What are some of the strengths and weaknesses of incentive policies?
When would these be the best policy tool to use?
Exercise:
Problem:
Did Coase think government policy was not necessary to solve
externality problems? Briefly explain.
Exercise:
Problem:
How do liability laws function as incentive policies? What are some of
their limitations?
References
Coase, R.H. 1960. The problem of social cost. Journal of Law and
Economics, 3, 1-44.
Glossary
ambient standard
A minimum level of overall environmental quality that must be
reached.
coase theorem
The idea that with property rights and frictionless negotiation, private
agents will bargain to reach efficient outcomes even in the face of
externalities.
command and control
Regulations that set strict, specific guidelines to govern the behavior of
polluters and resource users.
externality tax
A tax on something that causes negative externalities.
liability
A legal construct meaning that an agent is held responsible by the
courts to pay when that agent does something that imposes costs on
other people in society.
performance standard
A regulation specifying something about the outcome of private
behaviors.
technology standard
A regulation specifying what kind of technology agents must or must
not use in their activities.
tradable permits
A policy in which the total amount of an activity is limited, but agents
can trade the rights to engage in that activity (permits).
Modern Environmental Management — Chapter Introduction
In this module, the chapter Modern Environmental Management is
introduced.
Introduction
In the Chapter The Evolution of Environmental Policy in the United
States, the ways in which our current environmental policy evolved were
presented and discussed. Although the National Environmental Policy Act
(NEPA) provided lofty goals for our environmental policy, and most
importantly a legal basis for action, the fact remains, then and today, that
human actions produce very large quantities of waste, virtually all of it
harmful to human and ecosystem health if not managed properly. This
chapter is about how we currently manage these wastes (Module Systems
of Waste Management), the laws and regulations that define our system of
waste management (Module Government and Laws on the
Environment), and how we determine the consequences, i.e. risks,
associated with chemicals released into the environment (Module Risk
Assessment Methodology for Conventional and Alternative
Sustainability Options). Of course, environmental policies will continue to
evolve, and although we may not know the exact pathway or form this will
take, environmental policy of the future will most certainly build upon the
laws and regulations that are used today to manage human interactions with
the environment. Thus, it is important to develop an understanding of our
current system, its legal and philosophical underpinnings, and the
quantitative basis for setting risk-based priorities.
An interesting example of how our current system of environmental
management has adapted to modern, and global, problems is the U.S.
Supreme Court ruling, in April of 2007, in the case of Massachusetts vs. the
Environmental Protection Agency that the USEPA had misinterpreted the
Clean Air Act in not classifying, and regulating, carbon dioxide, as a
pollutant (the plaintiffs actually involved twelve states and several cities).
Up until that time several administrations had said that the Act did not give
the EPA legal authority to regulate CO, (and by inference all greenhouse
gases). At the time the Clean Air Act was passed (most recently in 1990),
"clean air" was thought to mean both visibly clean air, and also air free of
pollutants exposure to which could cause harm to humans — harm being
defined as an adverse outcome over a course of time that might extend to a
human lifetime. And although there was concern about global climate
change due to greenhouse gas emissions, the gases themselves were not
thought of as "pollutants" in the classical sense. This ruling set the stage for
the EPA to regulate greenhouse gases through a series of findings, hearings,
rulings, and regulations in accord with terms set out in the Clean Air Act.
This process is underway at the present time.
In addition to its significance for potentially mitigating the problem of
global climate change, this case illustrates more generally how the
environmental management system we have put in place today might adapt
to problems of the future. Laws that are forward-thinking, not overly
proscriptive, and administratively flexible may well accommodate
unforeseen problems and needs. Of course, this does not preclude the
passage of new laws or amendments, nor does it imply that all our laws on
the environment will adapt in this way to future problems.
Systems of Waste Management
In this module, the following topics are covered: 1) the environmental
regulations governing the management of solid and hazardous wastes,
radioactive waste and medical waste, 2) the environmental concerns with
the growing quantities and improper management of wastes being
generated, and 3) integrated waste management strategies.
Learning Objectives
After reading this module, students should be able to
e recognize various environmental regulations governing the
management of solid and hazardous wastes, radioactive waste and
medical waste
e understand the environmental concerns with the growing quantities
and improper management of wastes being generated
e recognize integrated waste management strategies that consist of
prevention, minimization, recycling and reuse, biological treatment,
incineration, and landfill disposal
Introduction
Waste is an inevitable by-product of human life. Virtually every human
activity generates some type of material side effect or by-product. When the
materials that constitute these by-products are not useful or have been
degraded such that they no longer fulfill their original or other obvious
useful purpose, they are classified as a waste material.
Practically speaking, wastes are generated from a wide range of sources and
are usually classified by their respective sources. Common generative
activities include those associated with residences, commercial businesses
and enterprises, institutions, construction and demolition activities,
municipal services, and water/wastewater and air treatment plants, and
municipal incinerator facilities. Further, wastes are generated from
numerous industrial processes, including industrial construction and
demolition, fabrication, manufacturing, refineries, chemical synthesis, and
nuclear power/nuclear defense sources (often generating low- to high-level
radioactive wastes).
Population growth and urbanization (with increased industrial, commercial
and institutional establishments) contribute to increased waste production,
as do the rapid economic growth and industrialization throughout the
developing world. These social and economic changes have led to an ever-
expanding consumption of raw materials, processed goods, and services.
While these trends have, in many ways, improved the quality of life for
hundreds of millions of people, it has not come without drastic costs to the
environment. Proper management of a range of wastes has become
necessary in order to protect public health and the environment as well as
ensure sustained economic growth.
It is commonly believed that incineration and landfill disposal represent
preferred options in dealing with waste products; however, many wastes
have the potential to be recycled or re-used for some purpose or in some
manner. Some waste materials may be reclaimed or re-generated and used
again for their original or similar purpose, or they may be physically or
chemically changed and employed for alternative uses. As natural resources
continue to be depleted, and as incineration and landfill disposal options
become more costly and unsustainable, numerous economic and social
incentives are being promoted by government agencies to prevent or reduce
waste generation and develop new methods and technologies for recycling
and reusing wastes. Such efforts can have broader implications for energy
conservation and the reduction of greenhouse gas emissions that contribute
to global climate change, while concurrently fostering sustainable waste
management practices.
This section provides an overview of the existing regulatory framework
mandating the management of wastes, environmental concerns associated
with waste generation and management, and various alternatives for the
proper management of wastes. Recent developments towards the
development of sustainable waste management systems are also
highlighted. It should be mentioned here that although the content of this
section reflects the regulatory framework and practices within the United
States, similar developments and actions have occurred in other developed
countries and are increasingly being initiated in numerous developing
countries.
Regulatory Framework
During the course of the 20" century, especially following World War II,
the United States experienced unprecedented economic growth. Much of
the growth was fueled by rapid and increasingly complex industrialization.
With advances in manufacturing and chemical applications also came
increases in the volume, and in many cases the toxicity, of generated
wastes. Furthermore, few if any controls or regulations were in place with
respect to the handling of toxic materials or the disposal of waste products.
Continued industrial activity led to several high-profile examples of
detrimental consequences to the environment resulting from these
uncontrolled activities. Finally, several forms of intervention, both in the
form of government regulation and citizen action, occurred in the early
1970s.
Ultimately, several regulations were promulgated on the state and federal
levels to ensure the safety of public health and the environment (see
Module Government and Laws on the Environment). With respect to
waste materials, the Resource Conservation and Recovery Act (RCRA),
enacted by the United States Congress, first in 1976 and then amended in
1984, provides a comprehensive framework for the proper management of
hazardous and non-hazardous solid wastes in the United States. RCRA
stipulates broad and general legal objectives while mandating the United
States Environmental Protection Agency (USEPA) to develop specific
regulations to implement and enforce the law. The RCRA regulations are
contained in Title 40 of the Code of Federal Regulations (CFR), Parts 239
to 299. States and local governments can either adopt the federal
regulations, or they may develop and enforce more stringent regulations
than those specified in RCRA. Similar regulations have been developed or
are being developed worldwide to manage wastes in a similar manner in
other countries.
The broad goals of RCRA include: (1) the protection of public health and
the environment from the hazards of waste disposal; (2) the conservation of
energy and natural resources; (3) the reduction or elimination of waste; and
(4) the assurance that wastes are managed in an environmentally-sound
manner (e.g. the remediation of waste which may have spilled, leaked, or
been improperly disposed). It should be noted here that the RCRA focuses
only on active and future facilities and does not address abandoned or
historical sites. These types of environmentally impacted sites are managed
under a different regulatory framework, known as the Comprehensive
more commonly known as "Superfund."
Solid Waste Regulations
RCRA defines solid waste as any garbage or refuse, sludge from a
wastewater treatment plant, water supply treatment plant, or air pollution
control facility and other discarded material, including solid, liquid, semi-
solid, or contained gaseous material resulting from industrial, commercial,
mining, and agricultural operations, and from community activities. In
general, solid waste can be categorized as either non-hazardous waste or
hazardous waste.
Non-hazardous solid waste can be trash or garbage generated from
residential households, offices and other sources. Generally, these materials
are Classified as municipal solid waste (MSW). Alternatively, non-
hazardous materials that result from the production of goods and products
by various industries (e.g. coal combustion residues, mining wastes, cement
kiln dust), are collectively known as industrial solid waste. The regulations
pertaining to non-hazardous solid waste are contained in 40 CFR Parts 239
to 259 (known as RCRA Subtitle D regulations).These regulations prohibit
the open dumping of solid waste, mandates the development of
comprehensive plans to manage MSW and non-hazardous industrial waste,
and establishes criteria for MSW landfills and other solid waste disposal
facilities. Because they are classified as non-hazardous material, many
components of MSW and industrial waste have potential for recycling and
re-use. Significant efforts are underway by both government agencies and
industry to advance these objectives.
Hazardous waste, generated by many industries and businesses (e.g. dry
cleaners and auto repair shops), is constituted of materials that are
dangerous or potentially harmful to human health and the environment. The
regulatory framework with respect to hazardous waste, specifically
hazardous waste identification, classification, generation, management, and
disposal, is described in 40 CFR Parts 260 through 279 (collectively known
as RCRA Subtitle C regulations). These regulations control hazardous
waste from the time they are generated until their ultimate disposal (a
timeline often referred to as "cradle to grave").
According to the RCRA Subtitle C regulations, solid waste is defined as
hazardous if it appears in one of the four hazardous waste classifications:
e F-List (non-specific source wastes as specified in 40 CFR 261.31),
which includes wastes from common manufacturing and industrial
processes, such as solvents used in cleaning and degreasing operations.
e K-list (source-specific waste as specified in 40 CFR 261.32), which
includes certain wastes from specific industries such as petroleum or
pesticide manufacturing.
e P-list and U-list (discarded commercial chemical products as specified
in 40 CFR 261.33), which include commercial chemicals products in
their unused form.
Additionally, a waste is classified as hazardous if it exhibits at least one of
these four characteristics:
¢ Ignitability (as defined in 40 CFR 261.21), which refers to creation of
fires under certain conditions; including materials that are
spontaneously combustible or those that have a flash point less than
140 OF.
¢ Corrosivity (as defined in 40 CFR 261.22), which refers to capability
to corrode metal containers; including materials with a pH less than or
equal to 2 or greater than or equal to 12.5.
e Reactivity (as defined in 40 CFR 261.23), which refers to materials
susceptible to unstable conditions such as explosions, toxic fumes,
gases, or vapors when heated, compressed, or mixed with water under
normal conditions.
e Toxicity (as defined in 40 CFR 261.24), which refers to substances that
can induce harmful or fatal effects when ingested or absorbed, or
inhaled.
Radioactive Waste Regulations
Although non-hazardous waste (MSW and industrial non-hazardous waste)
and hazardous waste are regulated by RCRA, nuclear or radioactive waste
is regulated in accordance with the Atomic Energy Act of 1954 by the
Radioactive wastes are characterized according to four categories: (1)
High-level waste (HLW), (2) ‘Transuranic waste (TRU), (3) Low-level
waste (LLW), and (4) Mill tailings. Various radioactive wastes decay at
different rates, but health and environmental dangers due to radiation may
persist for hundreds or thousands of years.
HLW is typically liquid or solid waste that results from government defense
related activities or from nuclear power plants and spent fuel assemblies.
These wastes are extremely dangerous due to their heavy concentrations of
radionuclides, and humans must not come into contact with them.
TRU mainly results from the reprocessing of spent nuclear fuels and from
the fabrication of nuclear weapons for defense projects. They are
characterized by moderately penetrating radiation and a decay time of
approximately twenty years until safe radionuclide levels are achieved.
Following the passage of a reprocessing ban in 1977, most of this waste
generation ended. Even though the ban was lifted in 1981, TRU continues
to be rare because reprocessing of nuclear fuel is expensive. Further,
because the extracted plutonium may be used to manufacture nuclear
weapons, political and social pressures minimize these activities.
LLW wastes include much of the remainder of radioactive waste materials.
They constitute over 80 percent of the volume of all nuclear wastes, but
only about two percent of total radioactivity. Sources of LLW include all of
the previously cited sources of HLW and TRU, plus wastes generated by
hospitals, industrial plants, universities, and commercial laboratories. LLW
is much less dangerous than HLW, and NRC regulations allow some very
low-level wastes to be released to the environment. LLW may also be
stored or buried until the isotopes decay to levels low enough such that it
may be disposed of as non-hazardous waste. LLW disposal is managed at
the state level, but requirements for operation and disposal are established
by the USEPA and NRC. The Occupational Health and Safety
Administration (OSHA) is the agency in charge of setting the standards for
workers that are exposed to radioactive materials.
Mill tailings generally consist of residues from the mining and extraction of
uranium from its ore. There are more than 200 million tons of radioactive
mill-tailings in the United States, and all of it is stored in sparsely populated
areas within the western states, such as Arizona, New Mexico, Utah, and
Wyoming. These wastes emit low-level radiation, and much of it is buried
to reduce dangerous emissions.
Medical Waste Regulations
Another type of waste that is of environmental concern is medical waste.
Medical waste is regulated by several federal agencies, including the
USEPA, OSHA, the Center for Disease Control and Prevention (CDC) of
the U.S. Department of Health and Human Services, and the Agency for
Service, U.S. Department of Health and Human Services. During 1987-88,
medical wastes and raw garbage washed up on beaches along the New
Jersey Shore of the United States on several occasions (called, "Syringe
Tide") which required closure of beaches. The U.S. Congress subsequently
enacted the Medical Waste Tracking Act (MWTA) to evaluate management
issues and potential risks related to medical waste disposal. The seven types
of wastes listed under MWTA include: (1) microbiological wastes (cultures
and stocks of infectious wastes and associated biological media that can
cause disease in humans); (2) human blood and blood products, including
serum, plasma, and other blood components; (3) pathological wastes of
human origin, including tissues, organs, and other body masses removed
during surgeries or autopsies); (4) contaminated animal wastes (i.e. animal
carcasses, body masses, and bedding exposed to infectious agents during
medical research, pharmaceutical testing, or production of biological
media); (5) isolation wastes (wastes associated with animals or humans
known to be infected with highly communicable diseases); (6)
contaminated sharps (including hypodermic needles, scalpels, and broken
glass); and (7) uncontaminated sharps. In addition, the USEPA considered
including any other wastes that had been in contact with infectious agents
or blood (e.g. sponges, soiled dressings, drapes, surgical gloves, laboratory
coats, slides).
LLW nuclear wastes are produced in hospitals by pharmaceutical
laboratories and in performing nuclear medicine procedures (e.g. medical
imaging to detect cancers and heart disease); however, the danger posed by
these wastes is relatively low. A variety of hazardous substances have also
been identified in medical wastes, including metals such as lead, cadmium,
chromium, and mercury; and toxic organics such as dioxins and furans. All
medical wastes represent a small fraction of total waste stream, estimated to
constitute a maximum of approximately two percent. Medical wastes are
commonly disposed of through incineration: as with most wastes, the
resulting volume is greatly reduced, and it assures the destruction and
sterilization of infectious pathogens. Disadvantages include the potential of
air pollution risks from dioxins and furans as well as the necessary disposal
of potentially hazardous ash wastes. New options for disposal of medical
wastes (including infectious wastes) are still being explored. Some other
technologies include irradiation, microwaving, autoclaving, mechanical
alternatives, and chemical disinfection, among others.
Environmental Concerns with Wastes
Managing Growing Waste Generation
An enormous quantity of wastes are generated and disposed of annually.
Alarmingly, this quantity continues to increase on an annual basis.
Industries generate and dispose over 7.6 billion tons of industrial solid
wastes each year, and it is estimated that over 40 million tons of this waste
is hazardous. Nuclear wastes as well as medical wastes are also increasing
in quantity every year.
Generally speaking, developed nations generate more waste than
developing nations due to higher rates of consumption. Not surprisingly, the
United States generates more waste per capita than any other country. High
waste per capita rates are also very common throughout Europe and
developed nations in Asia and Oceania. In the United States, about 243
million tons (243 trillion kg) of MSW is generated per year, which is equal
to about 4.3 pounds (1.95 kg) of waste per person per day. Nearly 34
percent of MSW is recovered and recycled or composted, approximately 12
percent is burned a combustion facilities, and the remaining 54 percent is
disposed of in landfills. Waste stream percentages also vary widely by
region. As an example, San Francisco, California captures and recycles
nearly 75 percent of its waste material, whereas Houston, Texas recycles
less than three percent.
With respect to waste mitigation options, landfilling is quickly evolving
into a less desirable or feasible option. Landfill capacity in the United States
has been declining primarily due to (a) older existing landfills that are
increasingly reaching their authorized capacity, (b) the promulgation of
stricter environmental regulations has made the permitting and siting of
new landfills increasingly difficult, (c) public opposition (e.g. "Not In My
Backyard" or NIMBYism) delays or, in many cases, prevents the approval
of new landfills or expansion of existing facilities. Ironically, much of this
public opposition arises from misconceptions about landfilling and waste
disposal practices that are derived from environmentally detrimental
historic activities and practices that are no longer in existence. Regardless
of the degree or extent of justification, NIMBYism is a potent opposition
phenomenon, whether it is associated with landfills or other land use
activities, such as airports, prisons, and wastewater treatment facilities.
Effects of Improper Waste Disposal and Unauthorized Releases
Prior to the passage of environmental regulations, wastes were disposed
improperly without due consideration of potential effects on the public
health and the environment. This practice has led to numerous contaminated
sites where soils and groundwater have been contaminated and pose risk to
the public safety. Of more than 36,000 environmentally impacted candidate
sites, there are more than 1,400 sites listed under the Superfund program
National Priority List (NPL) which require immediate cleanup resulting
from acute, imminent threats to environmental and human health. The
USEPA identified about 2,500 additional contaminated sites that eventually
require remediation. The United States Department of Defense maintains
19,000 sites, many of which have been extensively contaminated from a
variety of uses and disposal practices. Further, approximately 400,000
underground storage tanks have been confirmed or are suspected to be
leaking, contaminating underlying soils and groundwater. Over $10 billion
(more than $25 billion in current dollars) were specifically allocated by
CERCLA and subsequent amendments to mitigate impacted sites. However,
the USEPA has estimated that the value of environmental remediation
exceeds $100 billion. Alarmingly, if past expenditures on NPL sites are
extrapolated across remaining and proposed NPL sites, this total may be
significantly higher — well into the trillions of dollars.
It is estimated that more than 4,700 facilities in the United States currently
treat, store or dispose of hazardous wastes. Of these, about 3,700 facilities
that house approximately 64,000 solid waste management units (SWMUs)
may require corrective action. Accidental spillage of hazardous wastes and
nuclear materials due to anthropogenic operations or natural disasters has
also caused enormous environmental damage as evidenced by the events
such as the facility failure in Chernobyl, Ukraine (formerly USSR) in 1986,
the effects of Hurricane Katrina that devastated New Orleans, Louisiana in
2005, and the 2011 Tohoku earthquake and tsunami in Fukushima, Japan.
Adverse Impacts on Public Health
A wide variety of chemicals are present within waste materials, many of
which pose a significant environmental concern. Though the leachate
generated from the wastes may contain toxic chemicals, the concentrations
and variety of toxic chemicals are quite small compared to hazardous waste
sites. For example, explosives and radioactive wastes are primarily located
at Department of Energy (DOE) sites because many of these facilities have
been historically used for weapons research, fabrication, testing, and
training. Organic contaminants are largely found at oil refineries, or
petroleum storage sites, and inorganic and pesticide contamination usually
is the result of a variety of industrial activities as well as agricultural
activities. Yet, soil and groundwater contamination are not the only direct
adverse effects of improper waste management activities — recent studies
have also shown that greenhouse gas emissions from the wastes are
significant, exacerbating global climate change.
A wide range of toxic chemicals, with an equally wide distribution of
respective concentrations, is found in waste streams. These compounds may
be present in concentrations that alone may pose a threat to human health or
may have a synergistic/cumulative effect due to the presence of other
compounds. Exposure to hazardous wastes has been linked to many types
of cancer, chronic illnesses, and abnormal reproductive outcomes such as
birth defects, low birth weights, and spontaneous abortions. Many studies
have been performed on major toxic chemicals found at hazardous waste
sites incorporating epidemiological or animal tests to determine their toxic
effects.
As an example, the effects of radioactive materials are classified as somatic
or genetic. The somatic effects may be immediate or occur over a long
period of time. Immediate effects from large radiation doses often produce
nausea and vomiting, and may be followed by severe blood changes,
hemorrhage, infection, and death. Delayed effects include leukemia, and
many types of cancer including bone, lung, and breast cancer. Genetic
effects have been observed in which gene mutations or chromosome
abnormalities result in measurable harmful effects, such as decreases in life
expectancy, increased susceptibility to sickness or disease, infertility, or
even death during embryonic stages of life. Because of these studies,
occupational dosage limits have been recommended by the National
Council on Radiation Protection. Similar studies have been completed for a
wide range of potentially hazardous materials. These studies have, in turn,
been used to determine safe exposure levels for numerous exposure
scenarios, including those that consider occupational safety and remediation
standards for a variety of land use scenarios, including residential,
commercial, and industrial land uses.
Adverse Impacts on the Environment
The chemicals found in wastes not only pose a threat to human health, but
they also have profound effects on entire eco-systems. Contaminants may
change the chemistry of waters and destroy aquatic life and underwater eco-
systems that are depended upon by more complex species. Contaminants
may also enter the food chain through plants or microbiological organisms,
and higher, more evolved organisms bioaccumulate the wastes through
subsequent ingestion. As the contaminants move farther up the food chain,
the continued bioaccumulation results in increased contaminant mass and
concentration. In many cases, toxic concentrations are reached, resulting in
increased mortality of one or more species. As the populations of these
species decrease, the natural inter-species balance is affected. With
decreased numbers of predators or food sources, other species may be
drastically affected, leading to a chain reaction that can affect a wide range
of flora and fauna within a specific eco-system. As the eco-system
continues to deviate from equilibrium, disastrous consequences may occur.
Examples include the near extinction of the bald eagle due to persistent
ingestion of DDT-impacted fish, and the depletion of oysters, crabs, and
fish in Chesapeake Bay due to excessive quantities of fertilizers, toxic
chemicals, farm manure wastes, and power plant emissions.
Waste Management Strategies
The long-recognized hierarchy of management of wastes, in order of
preference consists of prevention, minimization, recycling and reuse,
biological treatment, incineration, and landfill disposal (see Figure
Hierarchy of Waste Management).
most
favoured
option
prevention
minimisation
recycling
feat energy recovery
favoured
option disposal
Hierarchy of Waste Management Figure shows
the hierarchy of management of wastes in order or
preference, starting with prevention as the most
favorable to disposal as the least favorable option.
Source: Drstuey via Wikimedia Commons
Waste Prevention
The ideal waste management alternative is to prevent waste generation in
the first place. Hence, waste prevention is a basic goal of all the waste
management strategies. Numerous technologies can be employed
throughout the manufacturing, use, or post-use portions of product life
cycles to eliminate waste and, in turn, reduce or prevent pollution. Some
representative strategies include environmentally conscious manufacturing
methods that incorporate less hazardous or harmful materials, the use of
modern leakage detection systems for material storage, innovative chemical
neutralization techniques to reduce reactivity, or water saving technologies
that reduce the need for fresh water inputs.
Waste Minimization
In many cases, wastes cannot be outright eliminated from a variety of
processes. However, numerous strategies can be implemented to reduce or
minimize waste generation. Waste minimization, or source reduction,
refers to the collective strategies of design and fabrication of products or
services that minimize the amount of generated waste and/or reduce the
toxicity of the resultant waste. Often these efforts come about from
identified trends or specific products that may be causing problems in the
waste stream and the subsequent steps taken to halt these problems. In
industry, waste can be reduced by reusing materials, using less hazardous
substitute materials, or by modifying components of design and processing.
Many benefits can be realized by waste minimization or source reduction,
including reduced use of natural resources and the reduction of toxicity of
wastes.
Waste minimization strategies are extremely common in manufacturing
applications; the savings of material use preserves resources but also saves
significant manufacturing related costs. Advancements in streamlined
packaging reduces material use, increased distribution efficiency reduces
fuel consumption and resulting air emissions. Further, engineered building
materials can often be designed with specific favorable properties that,
when accounted for in overall structural design, can greatly reduce the
overall mass and weight of material needed for a given structure. This
reduces the need for excess material and reduces the waste associated with
component fabrication.
The dry cleaning industry provides an excellent example of product
substitution to reduce toxic waste generation. For decades, dry cleaners
used tetrachloroethylene, or "perc" as a dry cleaning solvent. Although
effective, tetrachloroethylene is a relatively toxic compound. Additionally,
it is easily introduced into the environment, where it is highly recalcitrant
due to its physical properties. Further, when its degradation occurs, the
intermediate daughter products generated are more toxic to human health
and the environment.
Because of its toxicity and impact on the environment, the dry cleaning
industry has adopted new practices and increasingly utilizes less toxic
replacement products, including petroleum-based compounds. Further, new
emerging technologies are incorporating carbon dioxide and other relatively
harmless compounds. While these substitute products have in many cases
been mandated by government regulation, they have also been adopted in
response to consumer demands and other market-based forces.
Recycling and Reuse
Recycling refers to recovery of useful materials such as glass, paper,
plastics, wood, and metals from the waste stream so they may be
incorporated into the fabrication of new products. With greater
incorporation of recycled materials, the required use of raw materials for
identical applications is reduced. Recycling reduces the need of natural
resource exploitation for raw materials, but it also allows waste materials to
be recovered and utilized as valuable resource materials. Recycling of
wastes directly conserves natural resources, reduces energy consumption
and emissions generated by extraction of virgin materials and their
subsequent manufacture into finished products, reduces overall energy
consumption and greenhouse gas emissions that contribute to the global
climate change, and reduces the incineration or landfilling of the materials
that have been recycled. Moreover, recycling creates several economic
benefits, including the potential to create job markets and drive growth.
Common recycled materials include paper, plastics, glass, aluminum, steel,
and wood. Additionally, many construction materials can be reused,
including concrete, asphalt materials, masonry, and reinforcing steel.
"Green" plant-based wastes are often recovered and immediately reused for
mulch or fertilizer applications. Many industries also recover various by-
products and/or refine and "re-generate" solvents for reuse. Examples
include copper and nickel recovery from metal finishing processes; the
recovery of oils, fats, and plasticizers by solvent extraction from filter
media such as activated carbon and clays; and acid recovery by spray
roasting, ion exchange, or crystallization. Further, a range of used food-
based oils are being recovered and utilized in "biodiesel" applications.
Numerous examples of successful recycling and reuse efforts are
encountered every day. In some cases, the recycled materials are used as
input materials and are heavily processed into end products. Common
examples include the use of scrap paper for new paper manufacturing, or
the processing of old aluminum cans into new aluminum products. In other
cases, reclaimed materials undergo little or no processing prior to their re-
use. Some common examples include the use of tree waste as wood chips,
or the use of brick and other fixtures into new structural construction. In
any case, the success of recycling depends on effective collection and
processing of recyclables, markets for reuse (e.g. manufacturing and/or
applications that utilize recycled materials), and public acceptance and
promotion of recycled products and applications utilizing recycled
materials.
Biological Treatment
Landfill disposal of wastes containing significant organic fractions is
increasingly discouraged in many countries, including the United States.
Such disposal practices are even prohibited in several European countries.
Since landfilling does not provide an attractive management option, other
techniques have been identified. One option is to treat waste so that
biodegradable materials are degraded and the remaining inorganic waste
fraction (known as residuals) can be subsequently disposed or used for a
beneficial purpose.
Biodegradation of wastes can be accomplished by using aerobic
composting, anaerobicdigestion, or mechanical biological treatment
(MBT) methods. If the organic fraction can be separated from inorganic
material, aerobic composting or anaerobic digestion can be used to degrade
the waste and convert it into usable compost. For example, organic wastes
such as food waste, yard waste, and animal manure that consist of naturally
degrading bacteria can be converted under controlled conditions into
compost, which can then be utilized as natural fertilizer. Aerobic
composting is accomplished by placing selected proportions of organic
waste into piles, rows or vessels, either in open conditions or within closed
buildings fitted with gas collection and treatment systems. During the
process, bulking agents such as wood chips are added to the waste material
to enhance the aerobic degradation of organic materials. Finally, the
material is allowed to stabilize and mature during a curing process where
pathogens are concurrently destroyed. The end-products of the composting
process include carbon dioxide, water, and the usable compost material.
Compost material may be used in a variety of applications. In addition to its
use as a Soil amendment for plant cultivation, compost can be used
remediate soils, groundwater, and stormwater. Composting can be labor-
intensive, and the quality of the compost is heavily dependent on proper
control of the composting process. Inadequate control of the operating
conditions can result in compost that is unsuitable for beneficial
applications. Nevertheless, composting is becoming increasingly popular;
composting diverted 82 million tons of waste material away the landfill
waste stream in 2009, increased from 15 million tons in 1980. This
diversion also prevented the release of approximately 178 million metric
tons of carbon dioxide in 2009 — an amount equivalent to the yearly carbon
dioxide emissions of 33 million automobiles.
In some cases, aerobic processes are not feasible. As an alternative,
anaerobic processes may be utilized. Anaerobic digestion consists of
degrading mixed or sorted organic wastes in vessels under anaerobic
conditions. The anaerobic degradation process produces a combination of
methane and carbon dioxide (biogas) and residuals (biosolids). Biogas can
be used for heating and electricity production, while residuals can be used
as fertilizers and soil amendments. Anaerobic digestion is a preferred
degradation for wet wastes as compared to the preference of composting for
dry wastes. The advantage of anaerobic digestion is biogas collection; this
collection and subsequent beneficial utilization makes it a preferred
alternative to landfill disposal of wastes. Also, waste is degraded faster
through anaerobic digestion as compared to landfill disposal.
Another waste treatment alternative, mechanical biological treatment
(MBT), is not common in the United States. However, this alternative is
widely used in Europe. During implementation of this method, waste
material is subjected to a combination of mechanical and biological
operations that reduce volume through the degradation of organic fractions
in the waste. Mechanical operations such as sorting, shredding, and
crushing prepare the waste for subsequent biological treatment, consisting
of either aerobic composting or anaerobic digestion. Following the
biological processes, the reduced waste mass may be subjected to
incineration.
Incineration
Waste degradation not only produces useful solid end-products (such as
compost), degradation by-products can also be used as a beneficial energy
source. As discussed above, anaerobic digestion of waste can generate
biogas, which can be captured and incorporated into electricity generation.
Alternatively, waste can be directly incinerated to produce energy.
Incineration consists of waste combustion at very high temperatures to
produce electrical energy. The byproduct of incineration is ash, which
requires proper characterization prior to disposal, or in some cases,
beneficial re-use. While public perception of incineration can be negative,
this is often based reactions to older, less efficient technologies. New
incinerators are cleaner, more flexible and efficient, and are an excellent
means to convert waste to energy while reducing the volume of waste.
Incineration can also offset fossil fuel use and reduce greenhouse gas
(GHG) emissions (Bogner et al., 2007). It is widely used in developed
countries due to landfill space limitations. It is estimated that about 130
million tons of waste are annually combusted in more than 600 plants in 35
countries. Further, incineration is often used to effectively mitigate
hazardous wastes such as chlorinated hydrocarbons, oils, solvents, medical
wastes, and pesticides.
Despite all these advantages, incineration is often viewed negatively
because of the resulting air emissions, the creation of daughter chemical
compounds, and production of ash, which is commonly toxic. Currently,
many ‘next generation" systems are being researched and developed, and
the USEPA is developing new regulations to carefully monitor incinerator
air emissions under the Clean Air Act.
Landfill Disposal
Despite advances in reuse and recycling, landfill disposal remains the
primary waste disposal method in the United States. As previously
mentioned, the rate of MSW generation continues to increase, but overall
landfill capacity is decreasing. New regulations concerning proper waste
disposal and the use of innovative liner systems to minimize the potential of
groundwater contamination from leachate infiltration and migration have
resulted in a substantial increase in the costs of landfill disposal. Also,
public opposition to landfills continues to grow, partially inspired by
memories of historic uncontrolled dumping practices the resulting
undesirable side effects of uncontrolled vectors, contaminated groundwater,
unmitigated odors, and subsequent diminished property values.
Landfills can be designed and permitted to accept hazardous wastes in
accordance with RCRA Subtitle C regulations, or they may be designed and
permitted to accept municipal solid waste in accordance with RCRA
Subtitle D regulations. Regardless of their waste designation, landfills are
engineered structures consisting of bottom and side liner systems, leachate
collection and removal systems, final cover systems, gas collection and
removal systems, and groundwater monitoring systems (Sharma and Reddy,
2004). An extensive permitting process is required for siting, designing and
operating landfills. Post-closure monitoring of landfills is also typically
required for at least 30 years. Because of their design, wastes within
landfills are degraded anaerobically. During degradation, biogas is produced
and collected. The collection systems prevent uncontrolled subsurface gas
migration and reduce the potential for an explosive condition. The captured
gas is often used in cogeneration facilities for heating or electricity
generation. Further, upon closure, many landfills undergo "land recycling"
and redeveloped as golf courses, recreational parks, and other beneficial
uses.
Wastes commonly exist in a dry condition within landfills, and as a result,
the rate of waste degradation is commonly very slow. These slow
degradation rates are coupled with slow rates of degradation-induced
settlement, which can in turn complicate or reduce the potential for
beneficial land re-use at the surface. Recently, the concept of bioreactor
landfills has emerged, which involves recirculation of leachate and/or
injection of selected liquids to increase the moisture in the waste, which in
turn induces rapid degradation. The increased rates of degradation increase
the rate of biogas production, which increases the potential of beneficial
energy production from biogas capture and utilization.
Summary
Many wastes, such as high-level radioactive wastes, will remain dangerous
for thousands of years, and even MSW can produce dangerous leachate that
could devastate an entire eco-system if allowed infiltrate into and migrate
within groundwater. In order to protect human health and the environment,
environmental professionals must deal with problems associated with
increased generation of waste materials. The solution must focus on both
reducing the sources of wastes as well as the safe disposal of wastes. It is,
therefore, extremely important to know the sources, classifications,
chemical compositions, and physical characteristics of wastes, and to
understand the strategies for managing them.
Waste management practices vary not only from country to country, but
they also vary based on the type and composition of waste. Regardless of
the geographical setting of the type of waste that needs to be managed, the
governing principle in the development of any waste management plan is
resource conservation. Natural resource and energy conservation is
achieved by managing materials more efficiently. Reduction, reuse, and
recycling are primary strategies for effective reduction of waste quantities.
Further, proper waste management decisions have increasing importance, as
the consequences of these decisions have broader implications with respect
to greenhouse gas emissions and global climate change. As a result, several
public and private partnership programs are under development with the
goal of waste reduction through the adoption of new and innovative waste
management technologies. Because waste is an inevitable by-product of
civilization, the successful implementation of these initiatives will have a
direct effect on the enhanced quality of life for societies worldwide.
Review Questions
Exercise:
Problem:
How is hazardous waste defined according to the Resource
Conservation and Recovery Act (RCRA)? In your opinion, is this
definition appropriate? Explain.
Exercise:
Problem:
Explain specific characteristics of radioactive and medical wastes that
make their management more problematic than MSW.
Exercise:
Problem:
Compare and contrast environmental concerns with wastes in a rural
versus urban setting.
Exercise:
Problem:
What are the pros and cons of various waste management strategies?
Do you agree or disagree with the general waste management
hierarchy?
Exercise:
Problem:
Explain the advantages and disadvantages of biological treatment and
incineration of wastes.
References
Bogner, J., Ahmed, M.A., Diaz, C. Faaij, A., Gao, Q., Hashimoto,S., et al.
(2007). Waste Management, In B. Metz, O.R. Davidson, P.R. Bosch, R.
Dave, L.A. Meyer (Eds.), Climate Change 2007: Mitigation. Contribution
of Working Group III to the Fourth Assessment Report of the
Intergovernmental Panel on Climate Change (pp. 585-618). Cambridge
University Press, Cambridge, United Kingdom and New York, NY, USA.
Retrieved August 19, 2010 from http://www.ipcc.ch/pdf/assessment-
report/ar4/wg3/ar4-wg3-chapter10.pdf
Sharma, H.D. & Reddy, K.R. (2004). Geoenvironmental Engineering: Site
Remediation, Waste Containment, and Emerging Waste Management
Technologies. Hoboken, NJ: John Wiley.
Glossary
aerobic
Living systems or processes that require, or are not destroyed by, the
presence of oxygen.
anaerobic
A living system or process that occurs in, or is not destroyed by, the
absence of oxygen.
bioaccumulation
The increase in concentration of a substance in an organism over time.
biological treatment
A treatment technology that uses bacteria to consume organic fraction
of municipal solid waste/wastewater.
compost
The stable, decomposed organic material resulting from the
composting process.
corrosivity
The ability to corrode metal. Corrosive wastes are wastes that are
acidic and capable of corroding metal such as tanks, containers, drums,
and barrels.
digestion
The biochemical decomposition of organic matter of MSW, resulting
in its partial gasification, liquefaction, and mineralization.
genetic effects
Effects from some agent, like radiation that are seen in the offspring of
the individual who received the agent. The agent must be encountered
pre-conception.
high level radioactive waste (HLW)
The radioactive waste material that results from the reprocessing of
spent nuclear fuel, including liquid waste produced directly from
reprocessing and any solid waste derived from the liquid that contains
a combination of transuranic and fission product nuclides in quantities
that require permanent isolation.
ignitability
Ability to create fire under certain conditions. Ignitable wastes can
create fires under these certain conditions.
incineration
A thermal process of combusting MSW.
integrated waste management
A practice of using several alternative waste management techniques
to manage and dispose of MSW.
landfills
Designed, controlled and managed disposal sites for MSW spread in
layers, compacted to the smallest practical volume, and covered by
material applied at the end of each operating day.
leachate
Wastewater that collects contaminants as it trickles through MSW
disposed in a landfill.
low-level radioactive waste (LLW)
Radioactive waste material that is not high-level radioactive waste,
spent nuclear fuel, or byproduct material (see HLW).
mechanical biological treatment (MBT)
The process that combines sorting with a form of biological treatment
such as composting or anaerobic digestion.
medical waste
Any municipal solid waste generated in the diagnosis, treatment, or
immunisation of human beings or animals.
mill tailings
Waste material from a conventional uranium recovery facility.
municipal solid waste (MSW)
Includes non-hazardous waste generated in households, commercial
and business establishments, institutions, and non-hazardous industrial
process wastes, agricultural wastes and sewage sludge. Specific
definition is given in regulations.
pollution prevention
The active process of identifying areas, processes, and activities which
generate excessive waste for the purpose of substitution, alteration, or
elimination of the process to prevent waste generation in the first
place.
radioactive waste
Any waste that emits energy as rays, waves, or streams of energetic
particles.
reactivity
Materials susceptible to unstable conditions. Reactive wastes are
unstable under normal conditions and can create explosions and or
toxic fumes, gases, and vapors when mixed with water.
recycling
Separation physical/mechanical process by which secondary raw
materials (such as paper, metals, glass, and plastics.) are obtained from
MSW.
reuse
Using a component of MSW in its original form more than once.
solid waste
According to the Resource Conservation and Recovery Act (RCRA),
solid waste is: garbage; refuse; sludge from a waste treatment plant,
water supply treatment plant, or air pollution control facility; and other
discarded materials, including solid, liquid, or contained gaseous
material resulting from industrial, commercial, mining, and
agricultural operations, and from community activities.
somatic effects
Effects from some agent, like radiation that are seen in the individual
who receives the agent.
toxicity
The degree to which a chemical substance (or physical agent) elicits a
deleterious or adverse effect upon the biological system of an organism
exposed to the substance over a designated time period.
transuranic radioactive waste (TRU)
TRU waste contains more than 100 nanocuries of alpha-emitting
transuranic isotopes, with half-lives greater than twenty years, per
gram of waste.
waste to energy
Combustion of MSW to generate electrical energy or heat
waste minimization
Measures or techniques that reduce the amount of wastes generated
during industrial production processes; the term is also applied to
recycling and other efforts to reduce the amount of waste going into
the waste management system.
waste prevention
The design, manufacture, purchase or use of materials or products to
reduce their amount or toxicity before they enter the municipal solid
waste stream. Because it is intended to reduce pollution and conserve
resources, waste prevention should not increase the net amount or
toxicity of wastes generated throughout the life of a product.
Case Study: Electronic Waste and Extended Producer Responsibility
In this module, a case study about electronic waste and extended producer
responsibility is presented.
Electronic waste, commonly known as e-waste, refers to discarded
electronic products such as televisions, computers and computer peripherals
(e.g. monitors, keyboards, disk drives, and printers), telephones and cellular
phones, audio and video equipment, video cameras, fax and copy machines,
video game consoles, and others (see Figure
Electronic Waste).
ap vie) ts
Electronic Waste Photograph shows many computers piled up
in a parking lot as waste. Source: Bluedisk via Wikimedia
Commons
In the United States, it is estimated that about 3 million tons of e-waste are
generated each year. This waste quantity includes approximately 27 million
units of televisions, 205 million units of computer products, and 140 million
units of cell phones. Less than 15 to 20 percent of the e-waste is recycled or
refurbished; the remaining percentage is commonly disposed of in landfills
and/or incinerated. It should be noted that e-waste constitutes less than 4
percent of total solid waste generated in the United States. However, with
tremendous growth in technological advancements in the electronics
industry, many electronic products are becoming obsolete quickly, thus
increasing the production of e-waste at a very rapid rate. The quantities of
e-waste generated are also increasing rapidly in other countries such as
India and China due to high demand for computers and cell phones.
In addition to the growing quantity of e-waste, the hazardous content of e-
waste is a major environmental concern and poses risks to the environment
if these wastes are improperly managed once they have reached the end of
their useful life. Many e-waste components consist of toxic substances,
including heavy metals such as lead, copper, zinc, cadmium, and mercury as
well as organic contaminants, such as flame retardants (polybrominated
biphenyls and polybrominated diphenylethers). The release of these
substances into the environment and subsequent human exposure can lead
to serious health and pollution issues. Concerns have also been raised with
regards to the release of toxic constituents of e-waste into the environment
if landfilling and/or incineration options are used to manage the e-waste.
Various regulatory and voluntary programs have been instituted to promote
reuse, recycling and safe disposal of bulk e-waste. Reuse and refurbishing
has been promoted to reduce raw material use energy consumption, and
water consumption associated with the manufacture of new products.
Recycling and recovery of elements such as lead, copper, gold, silver and
platinum can yield valuable resources which otherwise may cause pollution
if improperly released into the environment. The recycling and recovery
operations have to be conducted with extreme care, as the exposure of e-
waste components can result in adverse health impacts to the workers
performing these operations. For economic reasons, recycled e-waste is
often exported to other countries for recovery operations. However, lax
regulatory environments in many of these countries can lead to unsafe
practices or improper disposal of bulk residual e-waste, which in turn can
adversely affect vulnerable populations.
In the United States, there are no specific federal laws dealing with e-waste,
but many states have recently developed e-waste regulations that promote
environmentally sound management. For example, the State of California
passed the Electronic Waste Recycling Act in 2003 to foster recycling,
reuse, and environmentally sound disposal of residual bulk e-waste. Yet, in
spite of recent regulations and advances in reuse, recycling and proper
disposal practices, additional sustainable strategies to manage e-waste are
urgently needed.
One sustainable strategy used to manage e-waste is extended producer
responsibility (EPR), also known as product stewardship. This concept
holds manufacturers liable for the entire life-cycle costs associated with the
electronic products, including disposal costs, and encourages the use of
environmental-friendly manufacturing processes and products.
Manufacturers can pursue EPR in multiple ways, including
reuse/refurbishing, buy-back, recycling, and energy production or beneficial
reuse applications. Life-cycle assessment and life-cycle cost methodologies
may be used to compare the environmental impacts of these different waste
management options. Incentives or financial support is also provided by
some government and/or regulatory agencies to promote EPR. The use of
non-toxic and easily recyclable materials in product fabrication is a major
component of any EPR strategy. A growing number of companies (e.g.
Dell, Sony, HP) are embracing EPR with various initiatives towards
achieving sustainable e-waste management.
EPR is a preferred strategy because the manufacturer bears a financial and
legal responsibility for their products; hence, they have an incentive to
incorporate green design and manufacturing practices that incorporate
easily recyclable and less toxic material components while producing
electronics with longer product lives. One obvious disadvantage of EPR is
the higher manufacturing cost, which leads to increased cost of electronics
to consumers.
There is no specific federal law requiring EPR for electronics, but the
United States Environmental Protection Agency (USEPA) undertook
several initiatives to promote EPR to achieve the following goals: (1) foster
environmentally conscious design and manufacturing, (2) increase
purchasing and use of more environmentally sustainable electronics, and (3)
increase safe, environmentally sound reuse and recycling of used
electronics. To achieve these goals, USEPA has been engaged in various
activities, including the promotion of environmental considerations in
product design, the development of evaluation tools for environmental
attributes of electronic products, the encouragement of recycling (or e-
cycling), and the support of programs to reduce e-waste, among others.
More than 20 states in the United States and various organizations
worldwide have already developed laws and/or policies requiring EPR in
some form when dealing with electronic products. For instance, the New
York State Wireless Recycling Act emphasizes that authorized retailers and
service providers should be compelled to participate in take-back programs,
thus allowing increased recycling and reuse of e-waste. Similarly, Maine is
the first U.S. state to adopt a household e-waste law with EPR.
In Illinois, Electronic Products Recycling & Reuse Act requires the
electronic manufacturers to participate in the management of discarded and
unwanted electronic products from residences. The Illinois EPA has also
compiled e-waste collection site locations where the residents can give
away their discarded electronic products at no charge. Furthermore, USEPA
compiled a list of local programs and manufacturers/retailers that can help
consumers to properly donate or recycle e-waste.
Overall, the growing quantities and environmental hazards associated with
electronic waste are of major concern to waste management professionals
worldwide. Current management strategies, including recycling and
refurbishing, have not been successful. As a result, EPR regulations are
rapidly evolving throughout the world to promote sustainable management
of e-waste. However, neither a consistent framework nor assessment tools
to evaluate EPR have been fully developed.
Government and Laws on the Environment
In this module, the following topics are covered: 1) the purpose of government regulations set for the protection of
human health and the environment; 2) current environmental laws and regulations for various types of pollutants,
and 3) the need for future environmental laws as related to the sustainability of industrial activity and the economy.
Learning Objectives
After reading this section, students should be able to
e understand the purpose of government regulations set for the protection of human health and the environment
e distinguish the current environmental laws and regulations for various types of pollutants present in different
media or phases of the environment
e discern the need for future environmental laws as related to the sustainability of industrial activity and the
economy
Introduction
In the United States, the laws and regulations pertaining to the protection of the environment have been enacted by
the U.S. Congress. The U.S. Environmental Protection Agency (EPA) is authorized to enforce the environmental
laws and to implement the environmental regulations. The United States environmental laws cover various phases
of the environment such as water, air, and hazardous waste, where most of the regulations have been based on the
risk assessment of the pollutants. The major environmental laws and regulations are briefly listed in the Table
Summary of Major Environmental Laws.
Environmental eseution oe Year
Issue P ym Enacted
Federal Water Pollution Control Act FWPC 1956
Water Amendment 1972
Clean Water Act ACWA 1972
a 1974
Drinking Water sate Dunne Wallen SDWA 1986,
Amendments
1996
: Clean Air Act 1955
mae Amendments EAS 1990
Resource Conservation and Recovery Act RCRA 1976
Hazardous and Solid Wastes Amendment HSWA 1984
Hazardous Wastes Comprehensive Environmental Response, CERCLA 1980
Compensation and Liability Act (Superfund)
Superfund Amendments and Reauthorization Act SARA 1986
Oil Spills Oil Pollution Act OPA 1990
Toxic Substances Toxic Substances Control Act TSCA 1976
Pesticides Federal Insecticide, Fungicide, and Rodenticide Act FIRFA 1972
Pollution Pollution Prevention Act PPA 1990
Prevention
Workplace Health Occupational Safety and Health Act OSHA 1970
and Safety Amendment 1990
Summary of Major Environmental Laws Table lists major environmental laws enacted from the 1950s onward.
Water
Clean Water Act
To protect the surface waters of the United States such as lakes, rivers, streams, shorelines and estuaries, the
Federal Water Pollution Control Act was established in 1956. The amendment to the Federal Water Pollution
Control Act (FWPCA) of 1972 focused on surface water quality goals, effluent limits based on available
technology, and a national discharge permit system. The FWPCA (1972) introduced effluent limits for chemical
substances in surface waters in conjunction with a National Pollutant Discharge Elimination System (NPDES)
allowing for enforceable control over permits obtained by industry for discharge of effluents containing pollutants
into natural water systems. The Clean Water Act (CWA) of 1977 placed emphasis on the control of waterborne
toxic substances released into natural surface waters. The CWA introduced a Priority List of Pollutants which
includes 127 toxic chemical substances including synthetic organic compounds and heavy metals. In accordance
with the CWA, the EPA must establish effluent limitations for chemical substances on the List of Priority
Pollutants for discharge by industrial facilities and municipal wastewater treatment plants.
The CWA aims to provide a system of national effluent standards for each industry, a set of water quality
standards, an enforceable discharge permit program, provisions for special wastes such as toxic chemicals and oil
spills, and a construction program for publicly owned treatment works (POTWs). Municipal wastewater treatment
plants are examples of POTWs. The NPDES permits are issued according to the effluent limitations required by
the Federal Water Pollution Control Act and the Clean Water Act. Because of higher costs associated with
treatment of industrial effluents before discharge into natural waters which requires an NPDES permit, many
industries discharge to a municipal sewer and have their wastes treated at the POTW following pretreatment
regulations overseen by the POTW. In addition, the CWA provides permits for stormwater and other non-point
source (see definition in Module "Sustainable Stormwater Management") pollution to prevent stormwater runoff
over contaminated land and paved areas from polluting surface waters such as rivers and lakes. Stormwater
pollution prevention plans and stormwater treatment facilities have to be implemented to avoid contamination of
clean water.
Safe Drinking Water Act (SDWA)
The Safe Drinking Water Act (SDWA) of 1974 was established to prevent potential contamination of groundwater,
which may serve as a source of drinking water. The SDWA amendments of 1986 and 1996 established standards
for water quality, which apply to drinking water as supplied by the public water supply systems. The groundwater
standards are also used to determine groundwater protection regulations under a number of other statutes. The EPA
has established a set of standards for unhealthful contaminants in drinking water referred to as the National
Primary Drinking Water Regulations (NPDWRs) as required by the SDWA amendment of 1986. The list of
regulated contaminants includes synthetic organic compounds, inorganic species such as heavy metals,
radionuclides, and pathogenic microorganisms. The NPDWR standards include both enforceable Maximum
Contaminant Levels (MCLs) and nonenforceable Maximum Contaminant Level Goals (MCLGs) used as health
goals. The MCLs are achieved in the drinking water treatment plant using the Best Available Technology (BAT)
for removal of the contaminants from water. Many of the drinking water MCLGs have also become the working
standards for organic and inorganic chemical contaminants as "Superfund" regulations for hazardous waste site
cleanups; Superfund regulations deal with the cleanup of abandoned sites containing hazardous wastes. Table
Example Drinking Water Standards lists the MCLs and MCLGs for several chemical contaminants. The Safe
Drinking Water Act amendment of 1986 also introduced Secondary Maximum Contaminant Levels (SMCLs) that
act as recommended maximum levels for contaminants, which do not have an adverse health effect but are mostly
related to esthetics of water (such as color and odor). The use of sound science and risk-based standard setting for
the NPDWRs is included in the SDWA amendment of 1996; new contaminants may be added in the future using a
list of candidate contaminants. In addition, the SDWA amendment of 1996 provides guidance to individual states
and industry toward protection of source water and well-head areas used for public water supply.
Organic MCL MCLG a al Inorganic MCL MCLG
Contaminant (mg/L) (mg/L) E pnt Contaminant (mg/L) (mg/L)
Benzene 0.005 Zero Cancer Arsenic 0.010 Zero
Liver, Ch :
Atrazine 0.003 0.003 kidney, a 0.1 0.1
lung (total)
Pentachlorophenol 0.001 Zero Cancer Cyanide 0.2 0.2
Polychlorinated :
biphenyls (PCBs) 0.0005 Zero Cancer Nitrate 10 10
Benzo(a)pyrene 0.0002 Zero Cancer Mercury 0.002 0.002
Example Drinking Water Standards (NPDWRs) Table lists the drinking water maximum contaminant levels and
contaminant level goals for a variety of chemical contaminants, along with the potential health effects that accompa
chemicals. Source: A. Khodadoust using data from U.S. EPA, 2011
Clean Air Act
The Clean Air Act (CAA) of 1955 and subsequent amendments were established to improve the quality of the air
resources in the United States. The CAA amendments of 1990 have provisions for maintenance of ambient air
quality to promote and improve public health. Enforcement of regulations is carried out through the use of
emission standards on stationary and mobile sources of air pollution that are directed at decreasing the production
of air contaminants from various sources. A National Ambient Air Quality Standard (NAAQS) is the maximum
permissible concentration of a contaminant in ambient air. Seven classes of air pollutants for which the NAAQS
has been established are referred to as criteria pollutants: lead, nitrogen oxides, sulfur oxides, ozone, particulate
matter smaller than 10 1m (PM) ), hydrocarbons and carbon monoxide. Some pollutants have short-term and long-
term standards designed to protect against acute and chronic health effects, respectively. In addition to criteria
pollutants, Hazardous Air Pollutants (HAPs) are those pollutants that are known or suspect carcinogens, or may
lead to other serious health effects over a longer period of exposure. The main sources of HAPs are industrial and
automotive emissions. The CAA amendments of 1990 have provisions for the reduction in emission of HAPs that
lead to lower concentrations of HAPs in ambient air.
The CAA amendments of 1990 established a permit program for larger sources of air emissions, where permits are
issued by states or by the EPA. Information on the types of pollutants that are emitted, the emission levels, the
monitoring of the emissions, and the plans to decrease the emissions is included in the permit. All applicable
information on the emissions and legal responsibilities of the business are conveyed by the permit system. The
1990 CAA amendments provide several market-based approaches to businesses to reach their pollution cleanup
thresholds such as pollution allowances that can be traded. In addition, economic incentives are provided to
businesses to trade the extra credit for operations requiring less cleanup in exchange with the lesser credit given for
operations requiring more cleanup.
The CAA aims to reduce emissions from mobile sources such as cars and other vehicles, and to develop cleaner
fuels. To maintain higher octane ranking in unleaded gasoline, the refiners have used more volatile fractions in
unleaded gasoline formulas, leading to release of volatile organic compounds (VOCs). Under the CAA
amendments of 1990, gasoline fuels are required to contain less volatile fractions, to contain oxyfuel compounds
(such as alcohol-based oxygenated compounds) for reduced production of carbon monoxide in cold weather, to
contain detergents for smoother running of engines, and to contain less sulfur in diesel fuel. The production of cars
capable of burning cleaner fuels such as natural gas or alcohol is mandated by the CAA amendments of 1990.
Emission of sulfur dioxide (SO) and nitrogen oxides (NOx) from combustion processes contribute to the
formation of acid rain. Most of the sulfur dioxide emitted annually in the United States is produced from the
burning of high-sulfur coal by electric utilities, resulting in acid rain with adverse impacts on the environment and
public health. Reduction of sulfur dioxide emissions is mandated by the CAA. Pollution allowances (up to
prescribed thresholds by EPA) for sulfur dioxide have been established by the EPA for each utility, where
allowances may be traded between utilities or within a company. Companies with emissions less than the EPA
allowance may trade their excess allowance with companies with allowance deficits, preventing severe hardships
to those utilities that that are dependent on high-sulfur coal. The CAA has also set provisions for reduction of NO,
emissions. A market-based approach is employed by the 1990 CAA amendments to eliminate ozone-destroying
chemical substances (such as chlorofluorocarbons) that deplete the ozone layer using a phasing-out schedule by
terminating the production of these chemicals in accordance with the Montreal Protocol (1989). The recycling of
chlorofluorocarbons (CFCs) and the labeling of ozone-friendly substitute chemicals are mandated by the CAA.
Hazardous Wastes
Hazardous wastes are wastes that pose a health and safety risk to humans and to the environment. The EPA
designates hazardous wastes as wastes which contain components that have one of the four general characteristics
of reactivity, corrosivity, ignitability and toxicity, in addition to other EPA classifications of hazardous wastes. The
laws and regulations governing the management of hazardous wastes and materials may be divided into two
categories: present and future hazardous materials and wastes are regulated under the Resource Conservation and
Recovery Act (RCRA), while past and usually abandoned hazardous waste sites are managed under the
Comprehensive Environmental Response, Compensation and Liability Act (CERCLA).
Resource Conservation and Recovery Act (RCRA)
The RCRA (1976) aims to achieve environmentally sound management of both hazardous and nonhazardous
wastes. As required by RCRA, the EPA established a cradle-to-grave (see Module Life Cycle Assessment)
hazardous material management system in an attempt to track hazardous material or waste from its point of
generation to its ultimate point of disposal, where the generators of hazardous materials have to attach a "manifest"
form to their hazardous materials shipments. The management of hazardous wastes including the transport,
treatment, storage and disposal of hazardous wastes is regulated under the RCRA. For hazardous wastes disposal,
this procedure will result in the shipment and arrival of those wastes at a permitted disposal site. The RCRA also
promotes the concept of resource recovery to decrease the generation of waste materials. The RCRA, as amended,
contains 10 subtitles. Subtitle C, for example, authorizes regulations for management of hazardous wastes and
Subtitle I deals with regulation of Underground Storage Tanks (USTs).
Hazardous waste management facilities receiving hazardous wastes for treatment, storage or disposal are referred
to as treatment, storage and disposal facilities (TSDFs). The EPA closely regulates the TSDFs so that they operate
properly for protection of human health and the environment. TSDF's may be owned and operated by independent
companies that receive wastes from a number of waste generators, or by the generators of waste themselves.
TSDFs include landfills, incinerators, impoundments, holding tanks, and many other treatment units designed for
safe and efficient management of hazardous waste. The EPA closely regulates the construction and operation of
these TSDFs, where the operators of TSDFs must obtain a permit from the EPA delineating the procedures for the
operation of these facilities. The operators must also provide insurance and adequate financial backing. The
shipping of wastes to a TSDF or recycler is frequently less expensive than obtaining and meeting all the
requirements for a storage permit.
The major amendment to Resource Conservation and Recovery Act was instituted in 1984 as the Hazardous and
Solid Waste Amendments (HSWA). The HSWA provides regulation for leaking underground storage tanks
(leaking USTs) affecting groundwater pollution. The RCRA regulates USTs containing hazardous wastes. The
HSWA added Subtitle I to RCRA to provide for regulation of new and existing UST systems, including corrosion
protection for all USTs to prevent the leaking of hazardous waste from corroded USTs. As part of the Superfund
Amendments Reauthorization Act (SARA, 1986), Subtitle I to RCRA was modified to provide for remedies and
compensation due to petroleum releases from UST systems. In addition, the HSWA provides for regulation to
prevent the contamination of groundwater by hazardous wastes, where the EPA restricts the disposal of hazardous
wastes in landfills due to the migration of hazardous constituents from the waste placed in landfills.
Comprehensive Environmental Response, Composition, and Liability Act (CERCLA)
The CERCLA (1980) also known as 'Superfund" aims to provide for liability, compensation and the cleanup of
inactive or abandoned hazardous waste disposal sites, and for emergency response to releases of hazardous
materials into the environment. CERCLA gives the EPA the power and the funding to clean up abandoned
hazardous waste sites and to respond to emergencies related to hazardous waste releases. The Superfund
Amendments and Reauthorization Act (SARA) of 1986 solidified many of the provisions of CERCLA such as
increasing the authority of the EPA to respond to remediation of hazardous waste sites with a faster startup for
cleanup of contaminated sites, and greatly increased the available trust fund for cleanup.
The EPA uses the National Priority List (NPL) to identify contaminated sites that present a risk to public health or
the environment and that may be eligible for Superfund money. A numeric ranking system known as the Hazard
Ranking System (HRS) has been established to determine the eligibility of contaminated sites for Superfund
money, where sites with high HRS scores are most likely to be added to the NPL. The National Contingency Plan
(NCP) provides guidance for the initial assessment and the HRS ranking of contaminated sites. After the initial
assessment of a contaminated site, a remedial investigation is carried out where the NCP provides for a detailed
evaluation of the risks associated with that site. A remedial investigation results in a work plan, which leads to the
selection of an appropriate remedy referred to as a feasibility study. The feasibility study assesses several remedial
alternatives, resulting in Record of Decision (ROD) as the basis for the design of the selected alternative. The
degree of cleanup is specified by the NCP in accordance with several criteria such as the degree of hazard to the
public health and the environment, where the degree of cleanup varies for different contaminated sites.
A separate addition to the provisions of CERCLA is Title III of SARA known as the Emergency Planning and
Community Right-to-Know Act (EPCRA). The State Emergency Response Commission must be notified by a
regulated facility that has extremely hazardous substances exceeding the EPA specified Threshold Planning
Quantities. The community is responsible for establishing Local Emergency Planning Committees to develop a
chemical emergency response plan which provides information on the regulated facilities, emergency response
procedures, training and evacuation plans. The awareness of a community about the specific chemicals present in
the community is an integral part of the Community's Right-to-Know, in addition to public information about
potential hazards from those chemicals. The EPCRA also stipulates that each year those facilities that release
chemicals above specified threshold levels should submit a Toxics Release Inventory (TRI) according to EPA
specifications. The TRI includes information on both accidental and routine releases in addition to off-site transfers
of waste. The availability of the TRI data to the public has led to serious consideration by industry to control their
previously unregulated and uncontrolled emissions due to the heightened public concern about the presence and
the releases of chemicals in their community.
Oil Pollution Act
The Oil Pollution Act (1990), or OPA, was established in response to the Exxon Valdez oil spill incident. The
Exxon Valdez oil spill (see Figure Exxon Valdez Oil Spill), which occurred in Alaska in 1989, was the largest
ever oil spill in the United States, causing major environmental and economic damage in Alaska.
Exxon Valdez Oil Spill Heavy sheens of oil covering large
areas of the Prince William Sound, Alaska a few days after
the Exxon Valdez oil spill. Source: U.S. National Oceanic
and Atmospheric Administration via Wikimedia Commons
The prevention of oil spills in navigable waters and shorelines of the United States is stipulated through the OPA
statute. The OPA encompasses oil spill prevention, preparedness, and response performance of industry and the
federal government. Incentives are provided to owners and operators for oil spill prevention, enforced by the EPA
through the oil spill liability and penalty provisions of the OPA. Oil companies in the United States engage in oil
exploration, both offshore and onshore, resulting in accidental releases of crude petroleum into the environment
from wells, drilling rigs, offshore platforms and oil tankers. With the exception of the 2010 BP Deepwater Horizon
oil spill in the Gulf of Mexico, the number and amount of oil spills have decreased over the past twenty years in
the United States despite the increasing demand for oil. This decline has been attributed to the OPA after the
Exxon Valdez oil spill incident. The Exxon Valdez oil spill was the largest ever in United States waters until the
2010 BP Deepwater Horizon oil spill (see Figure Deepwater Horizon Oil Spill). BP has been held to be
responsible for the Deepwater Horizon oil spill, and has been made accountable for all cleanup costs and other
damages by the federal government.
BP Deepwater Horizon Oil Spill The Deep Horizon oil spill in
the Gulf of Mexico as seen from space. Source: NASA/GSFC,
MODIS Rapid Response AND demis.nl AND FT2, via Wikimedia
Commons
Toxic Substances Control Act (TSCA)
Information on all chemical substances and the control of any of these substances which may have an unreasonable
health risk has been granted to the EPA through the Toxic Substances Control Act (1976). The manufacturer or the
importer of a new chemical must provide information on the identity and hazard, use, production volume and
disposal characteristics of the chemical to the EPA. Toxicological tests and unpublished health and safety studies
on listed chemicals may be required by the EPA. The EPA may approve, prohibit, or limit the manufacture and sale
of the listed chemicals, or may require special labeling. Since some chemical substances such as pesticides,
tobacco products, nuclear materials, pharmaceuticals and cosmetics substances are regulated under other acts, they
are exempted from TSCA regulations.
The production and distribution of polychlorinated biphenyls (PCBs) are prohibited through TSCA. PCBs are
synthetic organic compounds that were manufactured to be used as electrical transformer oil; exposure to PCBs
increases the risk of cancer, and may affect the reproductive and nervous systems. The EPA enforces the handling
and disposal of PCBs based on established regulations on PCBs, in addition to management of PCBs found at
hazardous waste sites. After the amendments of 1986 and 1990, TSCA through the Asbestos Hazard Emergency
Response Act requires that all public and commercial buildings identify, control and mitigate the asbestos hazard
in these buildings.
Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA)
Insecticides, fungicides and rodenticides are compounds that are employed to control or eliminate pest populations
(pesticides). The Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA) of 1972 with several subsequent
amendments set guidelines for the use of pesticides in the United States. All manufacturers or importers must
register their pesticide products with the EPA, where registration is allowed for a pesticide whose application does
not have unreasonable adverse effects on the environment. Industries such as the agricultural sector employ
pesticides to control vermin and other pests in industrial processes and in the workplace.
Pollution Prevention Act (PPA)
A pollution management system with a focus on generating less pollution at the source was established through the
Pollution Prevention Act (PPA) of 1990. The pollution prevention hierarchy stipulates that the first step in
reducing pollution is to minimize the amount of waste that is generated by all activities and processes, which is
referred to as source reduction. When the generation of waste cannot be reduced at the source, then the waste
should be recycled in order to decrease pollution. A waste that cannot be reduced at the source or recycled should
go through treatment and disposal in an environmentally safe manner. A Pollution Prevention Office has been
established by the EPA to promote source reduction as the preferred option in the pollution prevention hierarchy.
Pollution prevention is a voluntary measure on the part of the polluting industry rather than a mandatory regulatory
control enforced by the EPA and the individual states; industry is only required to file a toxic chemical source
reduction and recycling report with EPA every year. Industry is given incentives to institute pollution prevention
programs with the aim of realizing the economic benefits of pollution prevention to industry after the
implementation of pollution prevention programs.
Occupational Safety and Health Act (OSHA)
The Occupational Safety and Hazard Act (OSHA) of 1970 and its amendment of 1990 aim to ensure safe and
healthful working conditions for workers through enforcement of standards developed under OSHA, and to
provide for research, training and education in the field of occupational safety and health. The standards for
occupational health and safety are established by the Occupational Safety and Health Administration and its state
partners, which are enforced through inspections of industry and providing guidance on better operating practices.
The National Institute for Occupational Safety and Health (NIOSH) was established to recommend occupational
safety and health standards based on extensive scientific testing, which are afterwards enforced by OSHA. Those
industries which have followed OSHA standards have experienced a decline in overall injury and illness rates,
where the costs due to worker injuries, illnesses and compensation associated with occupational safety are a major
loss for industry. The OSHA standards for worker health and safety are recommended to be used in conjunction
with various industrial pollution prevention programs.
Summary
Environmental laws and regulations serve the purpose of limiting the amount of pollution in the environment from
anthropogenic sources due to industrial and other economic activities. Environmental regulations are specific to
different phases of the environment such as water and air. Government regulations help industry to curtail the
environmental impact of pollution, leading to the protection of human health and the environment. Future
environmental laws and policy should convey and work in tandem with the efforts of the public and industry for a
more sustainable economy and society.
Resources
1) For more information on environmental engineering, read Chapter 1 of:
Davis, M.L. & Comwell, D.A. (2008). Introduction to Environmental Engineering (4" ed.). New York: McGraw-
Hill.
2) For more information about managing environmental resources, read:
LaGrega, M.D., Buckingham, P.L., Evans, J.C., & Environmental Resources Management (2001). Hazardous
Waste Management (2 ed.). New York: McGraw-Hill.
3) For more information on the U.S. Environmental Protection Agency's laws and regulations, visit:
http://www.epa.gov/lawsregs/
Risk Assessment Methodology for Conventional and Alternative
Sustainability Options
In this module, the following topics are covered: 1) the content and the
goals of four-step of risk assessment process, 2) how to estimate dose
received via each exposure pathway, 3) how to integrate exposure and
toxicity information to characterize health risks, 4) how to quantitatively
estimate cumulative cancer and noncancer risks, and 5) how to
identify/evaluate uncertainties in risk assessment.
Learning Objectives
After reading this module, students should be able to
¢ understand the content and the goals of four-step of risk assessment
process
e know how to estimate dose received via each exposure pathway
e know how to integrate exposure and toxicity information to
characterize health risks
e understand how to quantitatively estimate cumulative cancer and
noncancer risks
e understand how to identify/evaluate uncertainties in risk assessment
Introduction
Risk assessment is a scientific process used by federal agencies and risk
management decision-makers to make informed decisions about actions
that may be taken to protect human health by ascertaining potential human
health risks or health hazard associated with exposure to chemicals in the
environment.
Smoke Stack Emissions into the
Atmosphere Figure shows emissions
billowing from a smoke stack into the
atmosphere. Risk assessment helps
federal agencies and risk management
decision-makers arrive at informed
decisions about actions to take to protect
human health from hazards such as air
pollution, pictured here. Source: Alfred
Palmer via Wikipedia
Some of the real-world examples of risk assessment includes: establishment
of national ambient air quality and drinking water standards for protection
of public health (e.g. ozone, particulate matter in outdoor air; chromium,
chloroform or benzene in water); establishment of clean-up levels for
hazardous waste site remediation; development of fish consumption
advisories for pregnant women and general population (e.g. PCBs,
mercury); assessment of risks and benefits of different alternative fuels for
sound energy policy development (e.g. oxygenated gasoline, biodiesel); and
estimation of health risks associated with pesticide residues in food. The
estimated risk is a function of exposure and toxicity, as described in detail
in NAS (1983) and EPA (1989). The regulatory risk assessment follows a
four-step paradigm using qualitative and/or quantitative approaches. In
quantitative risk assessment using either deterministic or probabilistic
approaches, the risk estimates pertaining to an exposure scenario is
particularly useful when comparing a number of exposure or risk reduction
measures among one another as an optimization protocol to determine the
best economically viable option for protection of public health and the
environment. With environmental sustainability and life-cycle analysis in
the forefront of green technological innovation, energy, and economic
savings in the 21%‘ Century, risk assessment will pay a pivotal role in
discerning the option(s) with the most benefit in health protection and, thus,
will be an integral part of any environmentally sustainability analysis. Such
comparative risk assessment can be performed for traditional approaches
vs. environmentally sustainable approaches. They can also be performed
among different environmentally sustainable options for an environmental
pollution problem such hazardous waste site remediation and
redevelopment, air quality management in urban areas, pest management
practices, agricultural health and safety, alternative energy sources for
transportation sources and among others.
The four steps of risk assessment are i) hazard identification; ii) toxicity (or
dose-response) assessment; iii) exposure assessment; and iv) risk
characterization, which are described below in detail. The emphasis is given
in documenting the resources necessary to successfully perform each step.
Hazard Identification
In the hazard identification step, a scientific weight of evidence analysis is
performed to determine whether a particular substance or chemical is or is
not causally linked to any particular health effect at environmentally
relevant concentrations. Hazard identification is performed to determine
whether, and to what degree, toxic effects in one setting will occur in other
settings. For example, is a chemical that is shown to cause carcinogenicity
in animal test species (e.g. rat, mouse) likely to be a carcinogen in exposed
humans? In order to assess the weight of evidence for adverse health
effects, risk analysts follow the following steps (EPA, 1993): (1) Compile
and analyze all the available toxicology data on the substance of interest;
(2) Weigh the evidence that the substance causes a toxic effect (cancer of
non-cancer health end-points); and (3) Assess whether adverse health effect
(or toxicity) could occur from human exposure in a real-life setting.
In the first task of hazard identification, risk analyst examines the toxicity
literature using the following analytical tools in the order of importance:
e Epidemiological studies
e Controlled human exposure chamber experiments
e In-vivo animal bioassays
e In-vitro cell and tissue culture bioassays
¢ Quantitative Structure —Activity Relationship Analysis (QSAR)
Among these, in-vivo animal bioassays are, by far, the most utilized source
of information for hazard identification for chemicals and, on rare
instances, for chemical mixtures (e.g. diesel). When available, well-
conducted epidemiological studies are regarded as the most valuable source
of human health hazard identification information since they provide direct
human evidence for potential health effects. Epidemiology is the study of
the occurrence and distribution of a disease or physiological condition in
human populations and of the factors that influence this distribution
(Lilienfeld and Lilienfeld, 1980). The advantages of epidemiological
studies for hazard identification are (EPA, 1989; EPA, 1993): animal-to-
human extrapolation is not necessary, real exposure conditions, and a wide
range of subjects with different genetic and life-style patterns. However,
epidemiological studies have a number of shortcomings, which limit their
usefulness in hazard identification. Some of these disadvantages include
difficulty in recruiting and maintaining a control group; having no control
over some of the non-statistical variables related to exposures, lifestyles,
co-exposure to other chemicals, etc.; absence of actual exposure
measurements along with memory bias for retrospective studies; lengthy
latency periods for chronic health effects such as cancer; and poor
sensitivity and inability to determine cause-effect relationships
conclusively.
Animal bioassays remedy some of the weaknesses of epidemiological
studies by allowing for greater control over the experiment and are deemed
to be reliable measurement of toxic effects, although they require "high
dose in animals-to low dose in humans" extrapolation. The selection of
design parameters of animal bioassays is critically important in observing
or missing an actual hazard. These parameters include: animal species
selected for the experiment (rat, mouse); strain of the test species; age/sex
of the test species; magnitude of exposure concentrations/doses applied or
administered; number of dose levels studied; duration of exposure; controls
selected; and route of exposure. Animal studies are characterized as acute (a
single dose or exposures of short duration), chronic (exposures for full
lifetimes of test species — about two years in rats/mice) and sub-chronic
(usually 90 days) based on the exposure duration. In the hazard
identification step, the following measures of toxicity are commonly
compiled:
¢ LD50/LC50/ECS50: The dose or concentration in a toxicity study at
which causing 50 percent mortality in test species was observed. The
ECs is the effective concentration causing adverse effects or
impairment in 50% of the test species.
e NOAEL (No Observable Adverse Effect Level): The highest dose or
concentration in a toxicity study at which no adverse effect was
observed.
¢ LOAEL (Lowest Observable Adverse Effect Level): The lowest dose
or concentration in a toxicity study at which an adverse effect was
observed.
e MTD (Maximum Tolerated Dose): The largest dose a test animal can
receive for most of its lifetime without demonstrating adverse health
effects other than carcinogenicity.
Risk scientists rely on a number of reputable sources to gather, compile, and
analyze hazard identification information to be able to perform weight of
evidence analysis and to conclude whether a chemical may cause a health
effect in humans. Some of these sources are:
¢ Hazardous Substances Data Bank (HSDB) maintained by the
National Library of Medicine: This scientifically peer-reviewed data
bank provides human and animal toxicity data for about 5,000
chemicals and can be accessed via http://toxnet.nlm.nih.gov/cgi-
bin/sis/htmlgen?HSDB
e ChemicIDplus Advanced database maintained by the National Library
of Medicine: This database allows users to search the NLM
ChemIDplus database of over 370,000 chemicals. Compound
identifiers such as Chemical Name, CAS Registry Number, Molecular
Formula, Classification Code, Locator Code, and Structure or
Substructure can be entered to display toxicity data via
http://chem.sis.nlm.nih.gov/chemidplus/
¢ National Toxicology Program (NTP) of the Department of Health and
Human Services:
o Report of Carcinogens (RoC): The RoC is an informational
scientific and public health document that identifies and discusses
agents, substances, mixtures, or exposure circumstances that may
pose a hazard to human health by virtue of their carcinogenicity.
The RoC is published biennially and serves as a meaningful and
useful compilation of data on: a) the carcinogenicity (ability to
cause cancer), genotoxicity (ability to damage genes), and
biologic mechanisms (modes of action in the body) of the listed
substance in humans and/or animals; b) the potential for human
exposure to these substances; and c) Federal regulations to limit
exposures. The link to the most recent version of the RoC can be
F1F6-975E-7CF8CBEACFOFC7EF
o NTP Toxicity Testing Study Results and Research Areas: NTP
tests chemicals for their toxicity in human and animal systems.
The results of these toxicity testing studies along with current
research areas can be obtained at:
CEBA-F7CC2DE0A230C920
e National Institute of Occupational and Safety Health (NIOSH) Hazard
Identification Databases: The following NIOSH website houses a
multitude of databases and information for chemicals and their hazards
under a single umbrella, including NIOSH's "Pocket Guide to
Chemical Hazards": http://www.cdc.gov/niosh/database.html
e Agency for Toxic Substances and Disease Registry (ATSDR)
Toxicological Profiles and Public Health Statements: ATSDR produces
"toxicological profiles" for hazardous substances found at National
Priorities List (NPL) Superfund sites. About 300 toxicological profiles
have so far been published or are under development. The chemical-
specific toxicological profiles can be accessed via
¢ World Health Organization (WHO) International Programme of
Chemical Safety (IPCS): ICPS publishes "Environmental Health
Criteria" (EHC) for chemical substances, which provide critical
reviews on the effects of chemicals or combinations of chemicals and
physical and biological agents on human health and the environment.
The IPCS site can be accessed via
http://www.who.int/ipcs/assessment/en/
e Material Safety Data Sheets (MSDS): MSDS are invaluable resource
to obtain compositional data for products and mixtures.
Toxicity (Dose-Response Assessment)
Dose-response assessment takes the toxicity data gathered in the hazard
identification step from animal studies and exposed human population
studies and describes the quantitative relationship between the amount of
exposure to a chemical (or dose) and the extent of toxic injury or disease (or
response). Generally, as the dose of a chemical increases, the toxic response
increases either in the severity of the injury or in the incidence of response
in the affected population (EPA, 1989; EPA, 1993). In toxicity-assessment
step, the relationship between the magnitude of the administered, applied,
or absorbed dose and the probability of occurrence and magnitude of health
effect(s) (e.g. tumor incidence in the case of cancer) is determined.
Dose-response assessment for carcinogens and non-carcinogens differ in
toxicity values use and how these toxicity values are derived. In general,
toxicity values provide a measure of toxic potency of the chemical in
question. These toxicity values are:
¢ Reference Dose (RfD) for oral/dermal pathways or Reference
Concentration (RfC) for inhalation pathway — Noncarcinogens: A
chronic RfD is defined as an estimate (with uncertainty spanning
perhaps an order of magnitude or greater) of a daily exposure level for
the human population, including sensitive subpopulations, that is likely
to be without an appreciable risk of deleterious effects during a
lifetime. It has the unit of mg of pollutant per kg of body weight per
day (mg/kg-day). Chronic RfDs are specifically developed to be
protective for long-term exposure to a chemical, usually, for exposure
periods between seven years (approximately 10 percent of a human
lifetime) and a lifetime. After selection of a critical health effect study
and a critical health effect through review of toxicity literature in the
hazard identification step, the RfD is derived by dividing the NOAEL
(or LOAEL) for the critical toxic effect by uncertainty factors (UFs)
and a modifying factor (MF). The uncertainty factors generally consist
of multiples of 10, with each factor representing a specific area of
uncertainty inherent in the extrapolation from the available data (e.g.
10 for extrapolation from animals to humans; 10 for interhuman
variability; 10 when LOAEL is used instead of NOAEL in deriving
RfD; 10 when NOAEL is obtained from a subchronic study rather than
a chronic study). A modifying factor ranging from >0 to 10 is included
to account for additional uncertainties in the critical study and in the
entire data based on a qualitative professional assessment. The default
value for the MF is 1. The NOAEL is selected based on the assumption
that if the critical toxic effect is prevented, then all toxic effects are
prevented (EPA, 1989). The derivation of toxicity value, RfD/RfC, for
noncarcinogens assumes that they are threshold chemicals, meaning
there is a threshold below which no adverse effects are observed in test
species. This dose level (i.e. NOAEL) in animals is simply adjusted by
a number of factors (UFs and MF) to determine the safe dose level in
humans (i.e. Rf{D) as shown by the following equation:
Equation:
NOAEL
ae UF |xUF)xUF3...xMF
e Cancer Slope Factor (CSF) for oral/dermal pathway or Unit Risk
Factor (URF) for inhalation pathway — Carcinogens: Unlike the
noncarcinogens, carcinogens assumed to be non-threshold chemicals
based on the Environmental Protection Agency (EPA) assumption that
a small number of molecular events can evoke changes in a single cell
that can lead to uncontrolled cellular proliferation and eventually to
cancer. In deriving slope factors, firstly, an appropriate dose-response
data set is selected. In this exercise, whenever available, human data of
high quality are preferable to animal data. However, if only animal
data are available, dose-response data from species that responds most
similarly to humans with respect to metabolism, physiology, and
pharmacokinetics is preferred. When no clear choice is possible, the
most sensitive species is chosen. Secondly, a model to the available
data set is applied and extrapolation from the relatively high doses
administered to test species in animal bioassay (or the exposures
recorded in epidemiologic studies) to the lower environmental
exposure levels expected for humans is performed using the model.
Although various models have been developed for this purpose (e.g.
probit, logit, Weibull), the linearized multistage model has commonly
been used by the EPA. After the data are fit to the appropriate model,
the upper 95" percent confidence limit of the slope of the resulting
dose-response curve is calculated, which is known as the Cancer Slope
Factor (CSF). It represents an upper 95" percent confidence limit on
the probability of a response per unit intake of a chemical over a
lifetime (i.e. dose). Thus, its units are (mg/kg-day) ~!. This indicates
that there is only a five percent chance that the probability of a
response could be greater than the estimated value of CSF. Because the
dose-response curve generally is linear only in the low-dose region, the
slope factor estimate only holds true for low doses. Toxicity values for
carcinogenic effects also can be expressed in terms of risk per unit
concentration of the chemical, which are called unit risk factors
(URFs). They are calculated by dividing the CSF by adult body weight
(70 kg) and multiplying by the adult inhalation rate (20 m?/day), for
risk associated with unit concentration in air (EPA, 1989).
A number of regulatory agencies responsible for environmental and public
health protection have devoted resources in developing and documenting
toxicity values for noncarcinogens (RfDs/RfCs) and carcinogens
(CSFs/URFs). The following hierarchy of sources is recommended by the
EPA in evaluating chemical toxicity for Superfund sites (EPA, 2003):
e Integrated Risk Information System (IRIS) and cited references, which
is the prime source for the chemical-specific toxicity value information
e The Provisional Peer Reviewed Toxicity Values (PPRTV) and cited
references developed for the EPA Office of Solid Waste and
Emergency Response (OSWER) Office of Superfund Remediation and
Technology Innovation (OSRTI) programs (not publicly available).
e Other toxicity values, which includes the following sources of toxicity
values that are commonly consulted by the EPA Superfund Program
when a relevant toxicity value is not available from either IRIS or the
PPRTV database:
o California Environmental Protection Agency (Cal EPA) Toxicity
Criteria Database, available at:
http://www.oehha.ca. gov/risk/chemicalDB/index.asp;
o The Agency for Toxic Substances and Disease Registry (ATSDR)
Minimal Risk Levels (MRLs, addressing noncancer effects only).
MRL is an estimate of the daily human exposure to a hazardous
substance that is likely to be without appreciable risk of adverse
noncancer health effects over a specified duration of exposure.
These substance-specific estimates, which are intended to serve as
screening levels, are used by ATSDR health assessors and other
responders to identify contaminants and potential health effects
that may be of concern at hazardous waste sites. To date, 137
inhalation MRLs, 226 oral MRLs and 8 external radiation MRLs
have been derived and can be found at:
http://www.atsdr.cdc. gov/mrls/index.html;
o The EPA Superfund Health Effects Assessment Summary Tables
(HEAST) database and cited references; and
o Additional sources of toxicity values.
There are a number of other valuable sources for toxicity values
(RfDs/RfCs for non-carcinogens and URFs/CSFs for carcinogens), which
can be compiled via the following sources:
e EPA Region 9 tabulated "Preliminary Remediation Goals (PRGs)"
or "Regional Screening Levels (RSL)" for Chemical Contaminants at
Superfund Sites," which also lists toxicity values (oral/inhalation RfD
and oral/inhalation CSF) used in the medium-specific PRG/RSL
calculation for each chemical. This table can be accessed via
http://www.epa.gov/region09/waste/sfund/pr¢g/index.html
e The Hot Spot Guidelines published by California EPA for Air Toxics
Program includes technical background documentation for toxicity
criteria/values for chemicals (i.e. Cancer Potency Factors (CPFs),
which is equivalent to EPA's CSFs and Chronic Recommended
Exposure Limits (RELs), which are similar to USEPA's RfCs). The
most recent version of REL Table is located at:
http://www.oebha.org/air/allrels.html. The Technical Support
Document for CPFs that contains cancer unit risks and potency factors
for 121 of the 201 carcinogenic substances or groups of substances can
be accessed via http://www.oehha.ca.gov/air/cancer_guide/TSD2.html.
e The Department of Energy's Oak Ridge National Laboratory
(ORNL) maintains Risk Assessment Information System (RAIS)
website, which contains useful information for risk assessment,
including chemical-specific toxicity values. The RAIS information can
be accessed via http://rais.ornl. gov/.
¢ Toxicology Excellence in Risk Assessment (TERA), a non-profit
organization, manages and distributes a free Internet database of
human health risk values and cancer classifications for over 600
chemicals of environmental concern from multiple organizations
worldwide. This database, Integrated Toxicity Estimates for Risk
(ITER), can be accessed via: http://www.tera.org/iter/ or via NLM's
TOXNET database at: http://toxnet.nlm.nih. gov.
The dermal RfDs and CSFs can be derived from oral RfDs and CSFs,
adjusted for chemical-specific gastrointestinal absorption efficiency, based
on the recommended methodology in EPA's Guidance for Dermal Risk
Assessment (EPA,_2004a).
Exposure Assessment
In the third step of risk assessment, the magnitude of exposure is
determined by measuring or estimating the amount of an agent to which
humans are exposed (i.e. exposure concentration) and the magnitude of
dose (or intake) is estimated by taking the magnitude, frequency, duration,
and route of exposure into account. Exposure assessments may consider
past, present, and future exposures.
Health effects of pollution
Air pollution
Water pollution
Soil
contamination
Human Health Effects of Environmental Pollution from
Pollution Source to Receptor Figure shows the human
health effects of environmental pollution from pollution
source to receptor. Source: Mikael Hdggstrom via
Wikimedia Commons
While estimates of past or current exposure concentration/dose can be
based on measurements or models of existing conditions, estimates of
future exposure concentration/dose can be based on models of future
conditions. In the case of inhalation exposures, personal or area monitoring
to sample for contaminants in the air can be employed. The sampling data
can be augmented with modeling efforts using default and/or site-specific
input parameters. The model application can begin with simple screening
level dispersion models and/or can utilize higher-level 2-D or 3-D models
depending on the complexity of the environmental pollution problem in
hand.
In any exposure assessment, the risk scientists ask a number of questions to
hypothesize the exposure scenario pertaining to environmental pollution
affecting the population or a sub-group. Some of these are:
e What is the source of pollution at the site? (e.g. underground storage
tank leak, emissions from an industrial plant, surface water run-off
from agricultural fields)
e¢ Which environmental compartments are likely to be contaminated?
(i.e. air, water, sediment, soil, plants, animals, fish)
e What are the chemicals of concern (COC) originating from the
pollution source?
e What are the fate and transport properties of these chemicals that may
inform the aging of the pollution in the environment over time and
resultant chemical signature in each environmental medium?
e Who is exposed? (e.g. children, elderly, asthmatics, general
population, workers)
e How many people are exposed?
e Where are people exposed? (e.g. home, workplace, outside
environment, retirement communities, schools)
e How are people exposed? (i.e. exposure pathway — inhalation, dermal
contact or ingestion)
¢ How often are people exposed? (i.e. exposure frequency)
¢ How long are people exposed? (i.e. exposure duration)
Answers to these questions frame the problem at hand. In the next step, a
number of exposure parameters are integrated into an estimate of daily dose
received by an exposed individual via each exposure route (ingestion,
dermal contact or skin absorption, and inhalation). The magnitude of human
exposures, in general, is dependent on COC concentration in soil, exposure
parameters describing human physiology (e.g. soil ingestion rate, body
weight), and population-specific parameters describing exposure behavior
(exposure frequency, duration). When evaluating subchronic or chronic
exposures to noncarcinogenic chemicals, dose is averaged over the period
of exposure, termed "Average Daily Dose" (ADD). However, for
carcinogens, dose is averaged over an entire lifetime (i.e. 70 years), thus
referred to as "Lifetime Average Daily Dose" (LADD). Both ADD and
LADD represent normalized exposure rate in the units of mg of chemical
per kg body weight per day (mg/kg-day). The ADD for noncarcinogenic
COCs and LADD for carcinogenic COCs are estimated for four most
commonly studied exposure pathways in EPA risk assessments, particularly
for hazardous waste sites, as shown below (Erdal, 2007):
Soil Ingestion: L(ADD), = ee
Dermal Contact: L(ADD) 4 = eee eh ea aca
. ‘ C,xIR;xEFxEDx (=
Inhalation of Particulates: L(ADD);, = ee ae
C,xIR;xEFxEDx(=)
Inhalation of Volatiles: L(ADD);, = BWxAT
Where:
C,: Exposure Concentration (i.e., 95th Upper Confidence Limit on the
Mean) of COC in soil (mg/kg) — (chemical-specific; can be estimated using
EPA 2004b)
IR,: Ingestion rate of soil (mg/d)
IR;: Inhalation rate (m?/d)
SA: Skin surface area (cm?)
AF: Soil-to-skin adherence factor (mg/cm?)
ABS: Dermal absorption fraction (unitless — chemical-specific)
EV: Event frequency (events/d)
EF: Exposure frequency (d/y)
ED: Exposure duration (y)
PEF: Particulate emission factor (m?/kg) — 1.36 x 10° m?/kg per (EPA
2002a)
VF: Soil-to-air volatilization factor (m?/kg — chemical-specific)
BW: Body weight (kg)
AT: Averaging time (days) — (ED*365 d/y for noncarcinogens; 70 y*365 d/y
for carcinogens)
CF: Conversion factor — 10° kg/mg
In deterministic risk assessment, ADD and LADD estimates are performed
for a reasonable maximum exposure scenario (RME) and a central tendency
exposure scenario (CTE), resulting in a range. EPA's reliance on the
concept of RME for estimating risks is based on a conservative but
plausible exposure scenario (which is defined to be the 90" to 95"
percentile exposure, signifying that fewer than five percent to 10 percent of
the population would be expected to experience higher risk levels), and has
been scientifically challenged over the years. For example, Burmaster and
Harris (1993) showed that the use of EPA recommended default exposure
parameter values resulted in exposure and risk estimates well in excess of
the 99" percentile due to multiplication of three upper-bound values (i.e.
95" percentiles) for IR, EF, and ED. The authors argued that this leads to
hazardous waste site cleanup decisions based on health risks that virtually
no one in the surrounding population would be expected to experience.
They advised the EPA to endorse and promote the use of probabilistic
methods (e.g. Monte-Carlo simulations) as a way to supplement or replace
current risk assessment methods, in order to overcome the problem of
"compounded conservatism" and enable calculation of risks using a more
statistically defensible estimate of the RME. In probabilistic risk
assessment, the input parameters are characterized by their unique
probability distribution. The EPA's Exposure Factors Program provides
information on development of exposure parameter distributions in support
of probabilistic distributions and can be accessed via:
http://cfpub.epa.gov/ncea/cfm/recordisplay.cfm?deid=20563.
The values of the exposure parameters corresponding to RME or CTE
scenarios are often compiled from EPA's Exposure Factors Handbook
(EFH):
e General Exposure Factors Handbook (EPA, 1997) provides exposure
assessors with data needed on standard factors to calculate human
exposure to toxic chemicals as part of risk assessments. These factors
include: drinking water consumption, soil ingestion, inhalation rates,
dermal factors including skin area and soil adherence factors,
consumption of fruits and vegetables, fish, meats, dairy products,
homegrown foods, breast milk intake, human activity factors,
consumer product use, and residential characteristics. Recommended
values are for the general population and also for various segments of
the population who may have characteristics different from the general
population. The most recent version of the EFH can be accessed via
http://cfpub.epa.gov/ncea/cfm/recordisplay.cfm?deid=209866.
e The Children-Specific EFH (EPA, 2002b) provides a summary of the
available and up-to-date statistical data on various factors assessing
child exposures, which can be accessed via
http://cfpub.epa. gov/ncea/cfm/recordisplay.cfm?deid=56747.
Risk Characterization
In the last step, a hazard quotient (HQ) as an indicator of risks associated
with health effects other than cancer and excess cancer risk (ECR) as the
incremental probability of an exposed person developing cancer over a
lifetime, are calculated by integrating toxicity and exposure information, as
shown below. If HQ > 1, there may be concern for potential adverse
systemic health effects in the exposed individuals. If HQ < 1, there may be
no concern. It should be noted that HQs are scaling factors and they are not
statistically based. The EPA's acceptable criterion for carcinogenic risks is
based on public policy as described in the National Contingency Plan
(NCP) and is the exposure concentration that represent an ECR in the range
of 10°*— 10°, i.e. 1 in 10,000 to 1 in 1,000,000 excess cancer cases (EPA,
1990).
Noncancer Risk: HazardQuotient(HQ) = =
Excess Cancer Risk (ECR): ECR = L(ADD)xCSF
To account for exposures to multiple COCs via multiple pathways,
individual HQs are summed to provide an overall Hazard Index (HI). If HI
>1, COCs are segregated based on their critical health end-point and
separate target organ-specific HIs are calculated. Only if target organ-
specific HI > 1, is there concern for potential health effects for that end-
point (e.g. liver, kidney, respiratory system).
Cumulative Noncancer Risk:
HazardIndex = HI = cocye=1 (HQ. + HQ, + HQ,)
Cumulative Excess Cancer Risk:
Here, o, d and i subscripts express oral (ingestion), dermal contact and
inhalation pathways.
As discussed above, the HQ, HI, and ECR estimates are performed for
RME and CTE scenarios separately in the case of deterministic risk
assessment. Although EPA published the probabilistic risk assessment
guidelines in 2001 (EPA, 2001), its application has so far been limited.
Proper evaluation of uncertainties, which are associated with compounded
conservatism and potential underestimation of quantitative risk estimates
(e.g. due to the presence of COCs without established toxicity values), is
intrinsic to any risk-based scientific assessment. In general, uncertainties
and limitations are associated with sampling and analysis, chemical fate and
transport, exposure parameters, exposure modeling, and human dose-
response or toxicity assessment (derivation of CSFs/RfDs, extrapolation
from high animal doses to low human doses), and site-specific
uncertainties.
Conclusion
The improvement in the scientific quality and validity of health risk
estimates depends on advancements in our understanding of human
exposure to, and toxic effects associated with, chemicals present in
environmental and occupational settings. For example, life-cycle of and
health risks associated with pharmaceuticals in the environment is poorly
understood due to lack of environmental concentration and human exposure
data despite extensive toxicological data on drugs. There are many other
examples for which either data on exposure or toxicity or both have not yet
been developed, preventing quantitative assessment of health risks and
development of policies that protect the environment and public health at
the same time. Therefore, it is important to continue to develop research
data to refine future risk assessments for informed regulatory decision-
making in environmental sustainability and to ensure that costs associated
with different technological and/or engineering alternatives are
scientifically justified and public health-protective. One area that,
particularly, requires advancement is the assessment of health risks of
chemical mixtures. Current risk assessment approaches consider one
chemical at a time. However, chemicals are present in mixtures in the
environment. Furthermore, physical, chemical and biological
transformations in the environment and interactions among chemicals in the
environment may change the toxic potential of the mixture over time. Thus,
risk assessment is an evolving scientific discipline that has many
uncertainties in all of the four steps. These uncertainties should be
thoroughly documented and discussed and the risk assessment results
should be interpreted within the context of these uncertainties.
Review Questions
Exercise:
Problem: What are the human health hazards of vinyl chloride?
Exercise:
Problem:
What are the human toxicity values (RfD, CSF) of vinyl chloride and
how are these values estimated?
Exercise:
Problem:
How do you calculate the dose received by children and adults via
ingestion of vinyl chloride-contaminated drinking water under the
RME scenario? Please document and explain your assumptions along
with your references for the exposure parameters for each receptor of
concer
Exercise:
Problem:
How do you calculate RME cancer and noncancer risks to children and
adults for the above exposure scenario?
Exercise:
Problem:
What does excess cancer risk of three cases out of ten thousand
exposed (3x10) signify?
Exercise:
Problem:
If drinking water were also contaminated with benzene, how would
you estimate cumulative cancer and noncancer risks associated with
exposure to drinking water contaminated with vinyl chloride and
benzene for children and adults under the RME scenario?
References
Burmaster, D.E. & Harris, R.H. (1993). The magnitude of compounding
conservatisms in Superfund risk assessments. Risk Analysis, 13, 131-34.
EPA (U.S. Environmental Protection Agency). (1989). Risk assessment
guidance for Superfund, volume I: Human health evaluation manual (Part
A) (Interim Final) (EPA/540/1-89002). Office of Emergency and Remedial
Response, Washington, DC
EPA (U.S. Environmental Protection Agency). (1990, March 8). National
contingency plan. Federal Register, 55, 8848. Washington, DC.
EPA (U.S. Environmental Protection Agency). (1993, September). SI 400:
Introduction to risk assessment and risk management for hazardous air
pollutants. Air Pollution Training Institute. Environmental Research Center,
Research Triangle Park, NC.
EPA (U.S. Environmental Protection Agency). (1997, August). Exposure
factors handbook, volume I — General factors (EPA/600/P-95/002Fa).
National Center for Environmental Assessment, Office of Research and
Development, Washington, DC.
EPA (U.S. Environmental Protection Agency). (2001, December). Risk
assessment guidance for Superfund, volume III — Part A: Process for
conducting probabilistic risk assessment (EPA540-R-02-002). Office of
Emergency and Remedial Response, Washington, DC.
EPA (U.S. Environmental Protection Agency). (2002a, December).
Supplemental guidance for developing soil screening levels for Superfund
sites (OSWER 9355.4-24). Office of Emergency and Remedial Response,
Washington, DC.
EPA (U.S. Environmental Protection Agency). (2002b, September). Child-
specific exposure factors handbook (EPA-600-P-00-002B). Interim Report.
National Center for Environmental Assessment, Office of Research and
Development, Washington, DC.
EPA (U.S. Environmental Protection Agency). (2003, December 5). Human
health toxicity values in Superfund risk assessments (OSWER Directive
9285.7-53). Memorandum from Michael B. Cook, Director of Office of
Superfund Remediation and Technology Innovation to Superfund National
Policy Managers, Regions 1 — 10. Office of Emergency and Remedial
Response, Washington, DC.
EPA (U.S. Environmental Protection Agency). (2004a, July). Risk
assessment guidance for Superfund, volume I: Human health evaluation
manual (Part E, supplemental guidance for dermal risk assessment)
(EPA/540/R/99/005). Final. Office of Superfund Remediation and
Technology Innovation, Washington, DC.
EPA (U.S. Environmental Protection Agency). (2004b, April). ProUCL
Version 3.00.02 user's guide and software (EPA/600/R04/079). Prepared by
Anita Singh and Robert Maichle with Lockheed Martin Environmental
Services and Ashok K. Singh of University of Nevada for the U.S.
Environmental Protection Agency.
Erdal, S. (2007). Case study: Multi-pathway risk assessment for adults and
children living near a hazardous waste site. In M.G. Robson & W.A.
Toscano (Eds.), Environmental Health Risk Assessment for Public Health
(pp. 523-530). Association of Schools of Public Health.
Lilienfeld A.M. & Lilienfeld, D.E. (1980). The French influence on the
development of epidemiology. Henry E Sigerist Supp! Bull Hist Med, 4, 28-
42.
NAS (National Academy of Sciences). (1983). Risk assessment in the
federal government: Managing the process. National Academy Press,
Washington, DC.
Glossary
bioassay
An assay for determining the potency (or concentration) of a substance
that causes a biological change in experimental animals.
carcinogenicity
Defines the ability or tendency to produce cancer.
chronic reference dose (RfD)
An estimate (with uncertainty spanning perhaps an order of
magnitude) of a daily oral exposure for a chronic duration (up to a
lifetime) to the human population (including sensitive subgroups) that
is likely to be without an appreciable risk of deleterious effects during
a lifetime. It can be derived from a NOAEL, LOAEL, or benchmark
dose, with uncertainty factors generally applied to reflect limitations of
the data used. Generally used in EPA's noncancer health assessments.
deterministic risk assessment
Risk evaluation involving the calculation and expression of risks as
single numerical values or "single point" estimates of risk, with
uncertainty and variability discussed qualitatively.
epidemiology
The study of the distribution and determinants of health-related states
or events in specified populations.
monte-carlo method
A repeated random sampling from the distribution of values for each
of the parameters in a generic (exposure or dose) equation to derive an
estimate of the distribution of (doses or risks in) the population.
probabilistic risk assessment
Risk evaluation involving the calculation and expression of risks using
multiple risk descriptors to provide the likelihood of various risk
levels. Probabilistic risk results approximate a full range of possible
outcomes and the likelihood of each, which often is presented as a
frequency distribution graph, thus allowing uncertainty or variability to
be expressed quantitatively.
Sustainable Energy Systems - Chapter Introduction
In this module, the following topics are presented: 1) an outline of the
history of human energy use, 2) challenges to continued reliance on fossil
energy, and 3) motivations and time scale for transitions in energy use.
Learning Objectives
After reading this module, students should be able to
e outline the history of human energy use
¢ understand the challenges to continued reliance on fossil energy
¢ understand the motivations and time scale for transitions in energy use
Introduction and History
Energy is a pervasive human need, as basic as food or shelter to human
existence. World energy use has grown dramatically since the rise of
civilization lured humans from their long hunter-gatherer existence to more
energy intensive lifestyles in settlements. Energy use has progressed from
providing only basic individual needs such as cooking and heating to
satisfying our needs for permanent housing, farming and animal husbandry,
transportation, and ultimately manufacturing, city-building, entertainment,
information processing and communication. Our present lifestyle is enabled
by readily available inexpensive fossil energy, concentrated by nature over
tens or hundreds of millions of years into convenient, high energy density
deposits of fossil fuels that are easily recovered from mines or wells in the
earth's crust.
Sustainability Challenges
Eighty five percent of world energy is supplied by combustion of fossil
fuels. The use of these fuels (coal since the middle ages for heating; and
coal, oil and gas since the Industrial Revolution for mechanical energy)
grew naturally from their high energy density, abundance and low cost. For
approximately 200 years following the Industrial Revolution, these energy
sources fueled enormous advances in quality of life and economic growth.
Beginning in the mid-20th Century, however, fundamental challenges began
to emerge suggesting that the happy state of fossil energy use could not last
forever.
Environmental Pollution
The first sustainability challenge to be addressed was environmental
pollution, long noticed in industrial regions but often ignored. Developed
countries passed legislation limiting the pollutants that could be emitted,
and gradually over a period of more than two decades air and water quality
improved until many of the most visible and harmful effects were no longer
evident.
Limited Energy Resources
The second sustainability issue to be addressed has been limited energy
resources. The earth and its fossil resources are finite, a simple fact with the
obvious implication that we cannot continue using fossil fuels indefinitely.
The question is not when the resources will run out, rather when they will
become too expensive or technically challenging to extract. Resources are
distributed throughout the earth's crust — some easily accessible, others
buried in remote locations or under impenetrable barriers. There are oil and
gas deposits in the Arctic, for example, that have not been explored or
documented, because until recently they were buried under heavy covers of
ice on land and sea. We recover the easy and inexpensive resources first,
leaving the difficult ones for future development. The cost-benefit balance
is usually framed in terms of peaking — when will production reach a peak
and thereafter decline, failing to satisfy rising demand, and thus create
shortages? Peaks in energy production are notoriously hard to predict
because rising prices, in response to rising demand and the fear of
shortages, provide increasing financial resources to develop more expensive
and technically challenging production opportunities.
Oil is a prime example of peaking. Although the peak in United States oil
production was famously predicted by M. King Hubbert 20 years before it
occurred, successful predictions of peaks in world oil production depend on
unknown factors and are notoriously difficult (Qwen, Inderwildi, & King,
2010; Hirsch, Bezdek, & Wendling, 2006). The fundamental challenges are
the unknown remaining resources at each level of recovery cost and the
unknown technology breakthroughs that may lower the recovery cost.
Receding Arctic ice and the growing ability to drill deeper undersea wells
promise to bring more oil resources within financial and technical reach,
but quantitative estimates of their impact are, at best, tentative.
800-
Billion Barrels
rt 8
° i
s
|
North Central Europe? CEurasia* Middle Africa Asia and
America’ and South East Oceania’
America
Crude Oil Reserves The global distribution of
crude oil resources. ! Includes 172.7 billion
barrels of bitumen in oil sands in Alberta,
Canada. * Excludes countries that were part of
the former U.S.S.R. See " Union of Soviet
Socialist Republics (U.S.S.R.)" in Glossary. °
Includes only countries that were part of the
former U.S.S.R.Source: U.S. Energy
Information Administration, Annual Review,
Uneven Geographical Distribution of Energy
The third sustainability challenge is the uneven geographical distribution of
energy resources. Figure Crude Oil Reserves shows the distribution of
crude oil reserves, with the Middle East having far more oil than any other
region and Europe and Asia, two high population and high demand regions,
with hardly any by comparison. This geographical imbalance between
energy resources and energy use creates uncertainty and instability of
supply. Weather events, natural disasters, terrorist activity or geopolitical
decisions can all interrupt supply, with little recourse for the affected
regions. Even if global reserves were abundant, their uneven geographical
distribution creates an energy security issue for much of the world.
CO, Emissions and Climate Change
The final and most recent concern is carbon dioxide emissions and climate
change (see Chapter Climate and Global Change). Since the
Intergovernmental Panel on Climate Change was established by the United
Nations in 1988, awareness of the links among human carbon dioxide
emissions, global warming and the potential for climate change has grown.
Climate scientists worldwide have documented the evidence of global
warming in surface air, land and sea temperatures, the rise of sea level,
glacier ice and snow coverage, and ocean heat content (Arndt, Baringer, &
Johnson, 2010). Figure Temperature, Sea Level, and Snow Cover 1850-
2000 shows three often quoted measures of global warming, the average
surface temperature, the rise of sea level and the northern hemisphere snow
cover.
Difference from 1961—1990
0.5} (a) Global average surface temperature 4414.5
13.5
(b) Global average sea level
4 4, (mm)
28 38
(c) Northern Hemisphere snow cover
Temperature, Sea Level, and Snow Cover 1850-
2000 Three graphs show trends in average surface
temperature, average sea level and northern
hemisphere snow cover from 1850-2000. Source:
Climate Change 2007: Synthesis Report:
Contribution of Working_Groups I, II and III to the
Fourth Assessment Report of the Intergovernmental
Press, figure 1.1, page 31
B
o
Temperature (°C)
(million km’)
There can be no doubt of the rising trends, and there are disturbing signs of
systematic change in other indicators as well (Arndt, et al., 2010). The
short-term extension of these trends can be estimated by extrapolation.
Prediction beyond thirty or so years requires developing scenarios based on
assumptions about the population, social behavior, economy, energy use
and technology advances that will take place during this time. Because
trends in these quantities are frequently punctuated by unexpected
developments such as the recession of 2008 or the Fukushima nuclear
disaster of 2011, the pace of carbon emissions, global warming and climate
change over a century or more cannot be accurately predicted. To
compensate for this uncertainty, predictions are normally based on a range
of scenarios with aggressive and conservative assumptions about the
degrees of population and economic growth, energy use patterns and
technology advances. Although the hundred year predictions of such
models differ in magnitude, the common theme is clear: continued reliance
on fossil fuel combustion for 85 percent of global energy will accelerate
global warming and increase the threat of climate change.
The present reliance on fossil fuels developed over time scales of decades
Hydroelectric
Power
Quadrillion Btu
0 =
1775 1800 1825 1850 1875 1900 1925 1950 1975 2000
Primary Energy Consumption by Source, 1775-2009 Graph shows
the pattern of fuel use in the United States since 1775. Source: U.S.
2010)
Wood was dominant for a century until the 1880s, when more plentiful,
higher energy density and less expensive coal became king. It dominated
until the 1950s when oil for transportation became the leading fuel, with
natural gas for heating a close second. Coal is now in its second growth
phase, spurred by the popularity of electricity as an energy carrier in the
second half of the 20" Century. These long time scales are built into the
energy system. Uses such as oil and its gasoline derivative for personal
transportation in cars or the widespread use of electricity take time to
establish themselves, and once established provide social and infrastructural
inertia against change.
The historical changes to the energy system have been driven by several
factors, including price and supply challenges of wood, the easy availability
and drop-in replaceability of coal for wood, the discovery of abundant
supplies of oil that enabled widespread use of the internal combustion
engine, and the discovery of abundant natural gas that is cleaner and more
transportable in pipelines than coal. These drivers of change are based on
economics, convenience or new functionality; the resulting changes in our
energy system provided new value to our energy mix.
The energy motivations we face now are of a different character. Instead of
adding value, the motivation is to avert "doomsday" scenarios of
diminishing value: increasing environmental degradation, fuel shortages,
insecure supplies and climate change. The alternatives to fossil fuel are
more expensive and harder to implement, not cheaper and easier than the
status quo. The historical motivations for change leading to greater value
and functionality are reversed. We now face the prospect that changing the
energy system to reduce our dependence on fossil fuels will increase the
cost and reduce the convenience of energy.
Summary
Continued use of fossil fuels that now supply 85 percent of our energy
needs leads to challenges of environmental degradation, diminishing energy
resources, insecure energy supply, and accelerated global warming.
Changing to alternate sources of energy requires decades, to develop new
technologies and, once developed, to replace the existing energy
infrastructure. Unlike the historical change to fossil fuel that provided
increased supply, convenience and functionality, the transition to alternative
energy sources is likely to be more expensive and less convenient. In this
chapter you will learn about the environmental challenges of energy use,
strategies for mitigating greenhouse gas emissions and climate change,
electricity as a clean, efficient and versatile energy carrier, the new
challenges that electricity faces in capacity, reliability and communication,
the challenge of transitioning from traditional fossil to nuclear and
renewable fuels for electricity production. You will also learn about the
promise of biofuels from cellulose and algae as alternatives to oil, heating
buildings and water with solar thermal and geothermal energy, and the
efficiency advantages of combining heat and power in a single generation
system. Lastly, you will learn about the benefits, challenges and outlook for
electric vehicles, and the sustainable energy practices that will reduce the
negative impact of energy production and use on the environment and
human health.
Review Questions
Exercise:
Problem:
Fossil fuels have become a mainstay of global energy supply over the
last 150 years. Why is the use of fossil fuels so widespread?
Exercise:
Problem:
Fossil fuels present four challenges for long-term sustainability. What
are they, and how do they compare in the severity of their impact and
cost of their mitigation strategies?
Exercise:
Problem:
The dominant global energy supply has changed from wood to coal to
oil since the 1700s. How long did each of these energy transitions take
to occur, and how long might a transition to alternate energy supplies
require?
References
Arndt, D. S., Baringer, M. O., & Johnson, M. R. (eds.). (2010). State of the
Climate in 2009. Bull. Amer. Meteor. Soc., 91, S1-S224,
Hirsch, R.L., Bezdek, R., & Wendling, R. (2006). Peaking of World Oil
Production and Its Mitigation. AIChE Journal, 52, 2 — 8. doi:
10.1002/aic.10747
Owen, N.A., Inderwildi, O.R., & King, D.A. (2010). The status of
conventional world oil reserves — Hype or cause for concern? Energy
Policy,38, 4743 — 4749. doi: 10.1016/j.enpol.2010.02.026
Glossary
fossil fuels
Oil, gas and coal produced by chemical transformation of land plants
(coal) and marine animals (oil and gas) trapped in the earth's crust
under high pressure and temperature and without access to oxygen.
The formation of fossil fuels can take.
industrial revolution
The transition from simple tools and animal power for producing
products to complex machinery powered by the combustion of fuels.
The Industrial Revolution began in England in the mid-18th Century
initially centered around the development of the steam engine powered
by coal.
internal combustion engine
The combustion of fuel inside or "internal" to the cylinder and moving
piston which produces motion; gasoline engines are a common
example. In contrast, steam engines are external combustion engines
where combustion and steam generation are outside the cylinder
containing the moving piston. The internal combustion engine is
lighter and more portable than the steam engine, enabling modern
transportation in cars, diesel powered trains, ships and airplanes.
peak oil / Hubbert's peak
A single oil well follows a pattern of increasing production in initial
years as its plentiful resources are tapped to declining production in
mature years as its resources are depleted. These two trends are
separated by a peak in production of the well. M. King Hubbert
extrapolated this pattern from one well to many and in 1956 predicted
that the United States’ oil production would peak in the mid-1970s.
Although widely criticized at the time, Hubbert's prediction proved
true. This success led to widespread predictions for the peak of world
oil production. The concept of peak oil is an inevitable consequence of
using oil faster than it can be made. However, attempts to predict when
the peak will occur are notoriously difficult.
Environmental Challenges in Energy, Carbon Dioxide, Air, Water and Land
Use
In this module, the following topics are addressed: 1) environmental
impacts of energy use, 2) energy sources based on their environmental
impact, and 3) the global capacity for each non-renewable energy source.
Learning Objectives
After reading this module, students should be able to
¢ outline environmental impacts of energy use
e evaluate the different energy sources based on their environmental
impact
¢ understand the global capacity for each non-renewable energy source
Introduction
Energy to illuminate, heat and cool our homes, businesses and institutions,
manufacture products, and drive our transportation systems comes from a
variety of sources that are originate from our planet and solar system. This
provides a social and economic benefit to society. The earth’s core provides
geothermal energy. The gravitational pull of moon and sun create tides.
The sun makes power in multiple ways. By itself, the sun generates direct
solar power. The sun’s radiation in combination with the hydrologic cycle
can make wind power and hydroelectric power. Through photosynthesis,
plants grow making wood and biomass that decay after they die into
organic matter. Over the course of thousands of years, this decay results in
fossil fuels that have concentrated or stored energy. To learn more about
measuring different kinds of energy, known as emergy, see Chapter
Problem-Solving, Metrics and Tools for Sustainability. Each of these
types of energy can be defined as renewable or non-renewable fuels and
they each have some environmental and health cost.
Fossil fuel reserves are not distributed equally around the planet, nor are
consumption and demand. We will see in this chapter that fuel distribution
is critical to the sustainability of fossil fuel resources for a given geographic
area. Access to renewable resources and their viability is greatly dependent
on geography and climate. Making energy requires an input of energy so it
is important to look at the net energy generated — the difference of the
energy produced less the energy invested.
Environmental and Health Challenges of Energy Use
The environmental impacts of energy use on humans and the planet can
happen anywhere during the life cycle of the energy source. The impacts
begin with the extraction of the resource. They continue with the
processing, purification or manufacture of the source, its transportation to
place of energy generation, effects from the generation of energy including
use of water, air, and land, and end with the disposal of waste generated
during the process. Extraction of fossil fuels, especially as the more
conventional sources are depleted, takes a high toll on the natural
environment. As we mine deeper into mountains, further out at sea, or
further into pristine habitats, we risk damaging fragile environments, and
the results of accidents or natural disasters during extraction processes can
be devastating. Fossils fuels are often located far from where they are
utilized so they need to be transported by pipeline, tankers, rail or trucks.
These all present the potential for accidents, leakage and spills. When
transported by rail or truck energy must be expended and pollutants are
generated. Processing of petroleum, gas and coal generates various types of
emissions and wastes, as well as utilizes water resources. Production of
energy at power plants results in air, water, and, often, waste emissions.
Power plants are highly regulated by federal and state law under the Clean
Air and Clean Water Acts, while nuclear power plants are regulated by the
Nuclear Regulatory Commission. As long as the facilities are complying,
much of the environmental impact is mitigated by treating the emissions
and using proper waste disposal methods. However, from a sustainability
perspective these still present environmental threats over the long run and
have a complex variety of issues around them. Figure Environmental
Impacts of Nonrenewable and Renewable Electricity Sources
summarizes these challenges. Later in the module, they are described more
fully for each source of energy and examples are given.
Qty
Pollutants & heat | Ash from plant,
ra clean
oan Rain run-off from
coal piles-lead &
arsenic
Oil 1,672 Pa lead, —_ Treated wastewater | Sludge from
from refineries refining & other
solid waste with
toxics & metals
Drilling can
contaminate
a 17 Methane Pollutants & heat
= —— Haz chemicals from
Paopel fracturing flow into
while Paopel surrounding ree
— Large | Plants, steam Heavy metals & salts | Radioactive waste
production, cooling in system i _
Waste from mining
contaminates water
Hydroele tric] eae
turbines
eat
build up
emman : Large | Steam & cooling Pollutants& heat | Reduceswaste to
Solid waste landfills but makes
possibly toxic ash
Biomass | Recyclescarbon, lessthan fossil uel | Large | Steam & cooling Pollutants& heat | Ash hay
pt
Solar Negligible None unless making steam Minimal haz waste Possibly
from cell wildlife
production
Geothermal | Neslizible Contamination from
drilling & extraction
Environmental Impacts of Nonrenewable and Renewable
Electricity Sources Source: C. Klein-Banai using data from U.S.
Energy Information Administration and U.S. Environmental Protection
Agency
= Spills during shipping
Geopolitical Challenges of Fossil Fuels
The use of fossil fuels has allowed much of the global population to reach a
higher standard of living. However, this dependence on fossil fuels results
in many significant impacts on society. Our modern technologies and
services, such as transportation, landscaping, and plastics production
depend in many ways on fossil fuels. Meaning, if supplies become limited
or extremely costly, our economies are vulnerable. If countries do not have
fossil fuel reserves of their own, they incur even more risk. The United
States has become more and more dependent on foreign oil since 1970
when our own oil production peaked. We imported over half of the crude oil
and refined petroleum products that we consumed during 2009. Just over
half of these imports came from the Western Hemisphere (see Figure
Sources of United States Net Petroleum Imports, 2009).
Sources of United States
Net Petroleum Imports,
2009 Figure illustrates that
the United States imported
over half of the crude oil
and refined petroleum
products that it consumed
during 2009. Source: U.S.
Energy Information
Administration, Petroleum
preliminary data
The holder of oil reserves in the oil market is the Organization of Petroleum
Exporting Countries, (OPEC) (see Figure Proven Oil Reserves Holders).
As of January 2009, there were 12 member countries in OPEC: Algeria,
Angola, Ecuador, Iran, Iraq, Kuwait, Libya, Nigeria, Qatar, Saudi Arabia,
the United Arab Emirates, and Venezuela. OPEC attempts to influence the
amount of oil available to the world by assigning a production quota to each
member except Iraq, for which no quota is presently set. Overall
compliance with these quotas is mixed since the individual countries make
the actual production decisions. All of these countries have a national oil
company but also allow international oil companies to operate within their
borders. They can restrict the amounts of production by those oil
companies. Therefore, the OPEC countries have a large influence on how
much of world demand is met by OPEC and non-OPEC supply. A recent
example of this is the price increases that occurred during the year 2011
after multiple popular uprisings in Arab countries, including Libya.
Former
Soviet
Union
countries
9%
Proven Oil Reserves Holders
Pie chart shows proven oil
reserves holders. Source: C.
Klein-Banai using data from
BP Statistical Review of World
Energy (2010)
This pressure has lead the United States to developing policies that would
reduce reliance on foreign oil such as developing additional domestic
sources and obtaining it from non-Middle Eastern countries such as Canada,
Mexico, Venezuela, and Nigeria. However, since fossil fuel reserves create
jobs and provide dividends to investors, a lot is at stake in a nation that has
these reserves. Depending on whether that oil wealth is shared with the
country’s inhabitants or retained by the oil companies and dictatorships, as
in Nigeria prior to the 1990s, a nation with fossil fuel reserves may benefit
or come out even worse.
Nonrenewable Energy and the Environment
Fossil fuels are also known as non-renewable energy because it takes
thousands of years for the earth to regenerate them. The three main fuel
sources come in all phases — solid, liquid, and gas — and will be discussed in
that order. One overriding concern is the carbon dioxide emissions that
contribute to climate change. Figure Fuel Type and Carbon Emissions
displays the relationship between fuel type and carbon emissions.
U.S. Energy Consumption by Resulting U.S. Energy-Related
Major Fuel Type, 2010 Carbon Dioxide Emissions by
Major Fuel Type, 2010
Fuel Type and Carbon Emissions The two charts show the
relationship between fuel type and carbon emissions for U.S. energy
consumption in 2010. Source: U.S. Energy Information Administration
Solid Fossil Fuel: Coal
Coal comes from organic matter that was compressed under high pressure
to become a dense, solid carbon structure over thousands to millions of
years. Due to its relatively low cost and abundance, coal is used to generate
about half of the electricity consumed in the United States. Coal is the
largest domestically produced source of energy. Figure Historic U.S. Coal
Production shows how coal production has doubled in the United States
over the last sixty year. Current world reserves are estimated at 826,000
million tonnes, with nearly 30 percent of that in the United States. It is a
major fuel resource that the United States controls domestically.
Million Short Tons
1200
1000 -
800 -
600
400
200
0
1950 1960 1970 1980 1990 2000 2010
Historic U.S. Coal Production Graph shows
U.S. Coal Production from 1950-2010. Source:
U.S. Energy Information Administration
Coal is plentiful and inexpensive, when looking only at the market cost
relative to the cost of other sources of electricity, but its extraction,
transportation, and use produces a multitude of environmental impacts that
the market cost does not truly represent. Coal emits sulfur dioxide, nitrogen
oxide, and mercury, which have been linked to acid rain, smog, and health
issues. Burning of coal emits higher amounts of carbon dioxide per unit of
energy than the use of oil or natural gas. Coal accounted for 35 percent of
the total United States emissions of carbon dioxide released into the Earth’s
atmosphere in 2010 (see Figure Fuel Type and Carbon Emissions). Ash
generated from combustion contributes to water contamination. Some coal
mining has a negative impact on ecosystems and water quality, and alters
landscapes and scenic views. There are also significant health effects and
risks to coal miners and those living in the vicinity of coal mines.
Traditional underground mining is risky to mine workers due to the risk of
entrapment or death. Over the last 15 years, the U.S. Mine Safety and
Health Administration has published the number of mine worker fatalities
and it has varied from 18-48 per year (see Figure U.S. Coal Mining
Related Fatalities).
Number of fatalities
Ww
=]
20
10
0
w wo ~ 2) a] So = ~“ ~o v w io ~ 0 oa] =)
7 OO O09 FO FS OBeescsecUcUOCUCOCUCUNUCOUUCUCO8UlUSM
nn); nn -) en -) en — — 2 — 2 — 2 — 2 2
= ~ -« =~ - N N ~N N ™N ~N ~N N MN N ™N
U.S. Coal Mining Related Fatalities Graph shows U.S.
coal mining related fatalities from 1995-2010. Source: C.
Klein-Banai using data from the U.S. Department of
Labor, Mine Safety and Health Administration
Twenty-nine miners died on April 6, 2010 in an explosion at the Upper Big
Branch coal mine in West Virginia, contributing to the uptick in deaths
between 2009 and 2010. In other countries, with less safety regulations,
accidents occur more frequently. In May 2011, for example, three people
died and 11 were trapped in a coalmine in Mexico for several days. There is
also risk of getting black lung disease (pneumoconiosis) This is a disease of
the lungs caused by the inhalation of coal dust over a long period of time. It
causes coughing and shortness of breath. If exposure is stopped the
outcome is good. However, the complicated form may cause shortness of
breath that gets increasingly worse.
Mountain Top Mining (MTM), while less hazardous to workers, has
particularly detrimental effects on land resources. MTM is a surface mining
practice involving the removal of mountaintops to expose coal seams, and
disposing of the associated mining waste in adjacent valleys — "valley fills."
The process of MTM is described in more detail by the U.S. Environmental
Protection Agency (U.S. EPA).
Mountaintop Removal Coal Mining in Martin County, Kentucky
Photograph shows mountaintop coal removal mining in Martin
County, Kentucky. Source: Flashdark.
The following are some examples of the impact of MTM:
¢ an increase of minerals in the water that negatively impact fish and
macroinvertebrates, leading to less diverse and more pollutant-tolerant
species
e streams are sometimes covered up by silt from mining
e the re-growth of trees and woody plants on regraded land may be
slowed due to compacted soils
e affects the diversity of bird and amphibian species in the area since the
ecosystem changes from wooded areas to other
e there may be social, economic and heritage issues created by the loss
of wooded land that may have been important to traditions and
economies of the area
accounting) for the life cycle of coal in the United States, accounting for
many environmental and health impacts of coal. The authors found the cost
to be about $0.178/kWh of electricity generated from coal ($345.4 billion in
2008), doubling or tripling the price of coal-generated electricity. This study
accounted for all of the impacts discussed above and more.
Liquid Fossil Fuel: Petroleum
Thirty seven percent of the world’s energy consumption and 43 percent of
the United States energy consumption comes from oil. As discussed above,
most of the oil production is in the Gulf region. Scientists and policy-
makers often discuss the question of when the world will reach peak oil
production, and there are a lot of variables in that equation, but it is
generally thought that peak oil will be reached by the middle of the 21°
Century. Currently world reserves are 1.3 trillion barrels, or 45 years left at
current level of production, but we may reduce production as supplies run
low.
Environmental Impacts of Oil Extraction and Refining
Oil is usually found one to two miles (1.6 — 3.2 km) below the surface. Oil
refineries separate the mix of crude oil into the different types for gas,
diesel fuel, tar, and asphalt. To find and extract oil workers must drill deep
below ocean floor. As the United States tries to extract more oil from its
own resources, we are drilling even deeper into the earth and increasing the
environmental risks.
The largest United States oil spill to date began in April 2010 when an
explosion occurred on Deepwater Horizon Oil Rig killing 11 employees and
spilling nearly 200 million gallons of oil before the resulting leak could be
stopped. Wildlife, ecosystems, and people’s livelihood were adversely
affected. A lot of money and huge amounts of energy and waste were
expended on immediate clean-up efforts. The long-term impacts are still not
known. The National Commission on the Deepwater Horizon Oil Spill and
Offshore Drilling was set up to study what went wrong. ‘This video
summarizes their findings.
Once oil is found and extracted it must be refined. Oil refining is one of top
sources of air pollution in the United States for volatile organic
hydrocarbons and toxic emissions, and the single largest source of
carcinogenic benzene.
When petroleum is burned as gasoline or diesel, or to make electricity or to
power boilers for heat, it produces a number of emissions that have a
detrimental effect on the environment and human health:
e Carbon dioxide (CO>) is a greenhouse gas and a source of climate
change.
e Sulfur dioxide (SO>) causes acid rain, which damages plants and
animals that live in water, and it increases or causes respiratory
illnesses and heart diseases, particularly in vulnerable populations like
children and the elderly.
e Nitrous oxides (NO,) and Volatile Organic Carbons (VOCs) contribute
to ozone at ground level, which is an irritatant and causes damage to
the lungs.
e Particulate Matter (PM) produces hazy conditions in cities and scenic
areas, and combines with ozone to contribute to asthma and chronic
bronchitis, especially in children and the elderly. Very small, or “fine
PM,” is also thought to penetrate the respiratory system more deeply
and cause emphysema and lung cancer.
e Lead can have severe health impacts, especially for children.
e Air toxins are known or probable carcinogens.
There are other domestic sources of liquid fossil fuel that are being
considered as conventional resources and are being depleted. These include
soil sands/tar sands — deposits of moist sand and clay with 1-2 percent
bitumen (thick and heavy petroleum rich in carbon and poor in hydrogen).
These are removed by strip mining (see section above on coal). Another
source is oil shale in United States west which is sedimentary rock filled
with organic matter that can be processed to produce liquid petroleum.
Also, mined by strip mines or subsurface mines, oil shale can be burned
directly like coal or baked in the presence of hydrogen to extract liquid
petroleum. However, the net energy values are low and they are expensive
to extract and process. Both of these resources have severe environmental
impacts due to strip mining, carbon dioxide, methane and other air
pollutants similar to other fossil fuels.
Gaseous Fossil Fuel: Natural Gas
Natural gas meets 20 percent of world energy needs and 25 percent of
United States needs. Natural gas is mainly composed of methane, the
shortest hydrocarbon (CH,), and is a very potent greenhouse gas. There are
two types of natural gas. Biogenic gas is found at shallow depths and arises
from anaerobic decay of organic matter by bacteria, like landfill gas.
Thermogenic gas comes from the compression of organic matter and deep
heat underground. They are found with petroleum in reservoir rocks and
with coal deposits, and these fossil fuels are extracted together.
Methane is released into the atmosphere from coal mines, oil and gas wells,
and natural gas storage tanks, pipelines, and processing plants. These leaks
are the source of about 25 percent of total U.S. methane emissions, which
translates to three percent of total U.S. greenhouse gas emissions. When
natural gas is produced but cannot be captured and transported
economically, it is "flared," or burned at well sites. This is considered to be
safer and better than releasing methane into the atmosphere because CO, is
a less potent greenhouse gas than methane.
In the last few years a new reserve of natural gas has been identified - shale
resources. The United States possesses 2,552 trillion cubic feet (Tcf) (72.27
trillion cubic meters) of potential natural gas resources, with shale resources
accounting for 827 Tcf (23.42 tcm). As gas prices increased it has become
more economical to extract the gas from shale. Figure U.S. Natural Gas
Supply,_1990-2035 shows the past and forecasted U.S. natural gas
production and the various sources. The current reserves are enough to last
about 110 years at the 2009 rate of U.S. consumption (about 22.8 Tcf per
year -645.7 bcm per year).
U.S. dry gas
trillion cubic
wa per year History 2009 Projections
|
shale gas
Non-associated onshore
Non-associated offshore
Tight gas
Coalbed methane
*
Assoociated with oil Alaska 1%~
1990 1995 2000 2005 2010 2015 2020 2025 2030 2035
U.S. Natural Gas Supply, 1990-2035 Graph shows U.S. historic and
projected natural gas production from various sources. Source: U.S.
Energy Information Administration
Natural gas is a preferred energy source when considering its environmental
impacts. Specifically, when burned, much less carbon dioxide (CO ),
nitrogen oxides, and sulfur dioxide are omitted than from the combustion of
coal or oil (see Table Environmental Impacts of Nonrenewable and
Renewable Electricity Sources). It also does not produce ash or toxic
emissions.
Environmental Impacts of Exploration, Drilling, and Production
Land resources are affected when geologists explore for natural gas deposits
on land, as vehicles disturb vegetation and soils. Road clearing, pipeline
and drill pad construction also affect natural habitats by clearing and
digging. Natural gas production can also result in the production of large
volumes of contaminated water. This water has to be properly handled,
stored, and treated so that it does not pollute land and water supplies.
Extraction of shale gas is more problematic than traditional sources due to a
process nicknamed “fracking,” or fracturing of wells, since it requires large
amounts of water (see Figure Hydraulic Fracturing Process). The
considerable use of water may affect the availability of water for other uses
in some regions and this can affect aquatic habitats. If mismanaged,
hydraulic fracturing fluid can be released by spills, leaks, or various other
exposure pathways. The fluid contains potentially hazardous chemicals
such as hydrochloric acid, glutaraldehyde, petroleum distillate, and ethylene
glycol. The risks of fracking have been highlighted in popular culture in the
documentary, Gasland (2010).
Fracturing also produces large amounts of wastewater, which may contain
dissolved chemicals from the hydraulic fluid and other contaminants that
require treatment before disposal or reuse. Because of the quantities of
water used and the complexities inherent in treating some of the wastewater
components, treatment and disposal is an important and challenging issue.
The raw gas from a well may contain many other compounds besides the
methane that is being sought, including hydrogen sulfide, a very toxic gas.
Natural gas with high concentrations of hydrogen sulfide is usually flared
which produces COs, carbon monoxide, sulfur dioxide, nitrogen oxides, and
many other compounds. Natural gas wells and pipelines often have engines
to run equipment and compressors, which produce additional air pollutants
and noise.
Roughly 200 tanker A pumper truck injects a Natural gas flows out of well.
trucks deliver water for mix of sand, water and sonsonsnnsqncensonsensenesnstansansansessensensensancencensensenenns ~ sie
: en Storage Natural gas is piped
the fracturing process. chemicals into the well. i Recovered water is stored in open
mi pits, then taken to a treatment tanks = to market.
————————we mil r 1
Pies
/ >
00° 00-0 O00 eye
1,000
Hydraulic Fracturing
oan Hydraulic fracturing, or
: “tracing,” involves the injection
of more than a million gallons
i of water, sand and chemicals
3,000 at high pressure down and
across into horizontally drilled
wells as far as 10,000 feet
s,000 below the surface. The
pressurized mixture causes
the rock layer, in this case the
5.000 Marcellus Shale, to crack.
These fissures are held open
by the sand particles so that
ee natural gas from the shale can
6,000 flow up the well.
7,000
Well turns
horizontal
Marcellus Shale
Hydraulic Fracturing Process Graphic illustrates the process of
hydraulic fracturing. Source: Al Granberg, ProPublica, This graphic
may not be relicensed for sale except by the copyright holder
(ProPublica).
Alternatives to Fossil Fuels
Nuclear Power
Nuclear power plants produce no carbon dioxide and, therefore, are often
considered an alternative fuel, when the main concern is climate change.
Currently, world production is about 19.1 trillion KWh, with the United
States producing and consuming about 22 percent of that. Nuclear power
provides about nine percent of our total consumption for electricity (see
Figure U.S. Energy Consumption by Energy Source, 2009).
However, there are environmental challenges with nuclear power. Mining
and refining uranium ore and making reactor fuel demands a lot of energy.
The plants themselves are made of metal and concrete which also requires
energy to make. The main environmental challenge for nuclear power is the
wastes including uranium mill tailings, spent (used) reactor fuel, and other
radioactive wastes. These materials have long radioactive half-lives and
thus remain a threat to human health for thousands of years. The U.S.
Nuclear Regulatory Commission regulates the operation of nuclear power
plants and the handling, transportation, storage, and disposal of radioactive
materials to protect human health and the environment.
By volume, uranium mill tailings are the largest waste and they contain the
radioactive element radium, which decays to produce radon, a radioactive
gas. This waste is placed near the processing facility or mill where they
come from, and are covered with a barrier of a material such as clay to
prevent radon from escaping into the atmosphere and then a layer of soil,
rocks, or other materials to prevent erosion of the sealing barrier.
High-level radioactive waste consists of used nuclear reactor fuel. This fuel
is in a solid form consisting of small fuel pellets in long metal tubes and
must be stored and handled with multiple containment, first cooled by water
and later in special outdoor concrete or steel containers that are cooled by
air. There is no long-term storage facility for this fuel in the United States.
There are many other regulatory precautions governing permitting,
construction, operation, and decommissioning of nuclear power plants due
to risks from an uncontrolled nuclear reaction. The potential for
contamination of air, water and food is high should an uncontrolled reaction
occur. Even when planning for worst-case scenarios, there are always risks
of unexpected events. For example, the March 2011 earthquake and
subsequent tsunami that hit Japan resulted in reactor meltdowns at the
Fukushima Daiichi Nuclear Power Station causing massive damage to the
surrounding area.
Note: Fukushima Daiichi Nuclear Power Station
e March 11, 2011: Magnitude 9.0 earthquake 231 miles northeast of
Tokyo. Less than 1 hour later a 14m tsunami hit
e 50 power station employees worked around the clock to try to
stabilize the situation
United States’ nuclear reactors have containment vessels that are designed
to withstand extreme weather events and earthquakes. However, in the
aftermath of the Japan incident, they are reviewing their facilities, policies,
and procedures.
Total = 94.578 Quadrillion Btu Total = 7.744 Quadrillion Btu
—Solar 1%
— Geothermal 5%
—-Biomass waste 6%
Wind 9%
Biofuels 20%
Renewable
Energy
Wood 24%
8% :
Nuclear
Electric Power
9%
Hydropower 35%
Note: Sum of components may not equal 100% due to independent rounding.
U.S. Energy Consumption by Energy Source, 2009 Renewable
energy makes up 8% of U.S. energy consumption. Source: U.S. Energy
Information Administration
Hydropower
Hydropower (hydro-electric) is considered a clean and renewable source of
energy since it does not directly produce emissions of air pollutants and the
source of power is regenerated. However, hydropower dams, reservoirs, and
the operation of generators can have environmental impacts. Figure Hoover
Power Plant shows the Hoover Power Plant located on the Colorado River.
Hydropower provides 35 percent of the United States’ renewable energy
consumption (see Figure U.S. Energy Consumption by Energy Source,
2009). In 2003 capacity was at 96,000 MW and it was estimated that 30,000
MW capacity is undeveloped.
Hoover Power Plant View of Hoover Power
Plant on the Colorado River as seen from
above. Source: U.S. Department of the Interior
Migration of fish to their upstream spawning areas can be obstructed by a
dam that is used to create a reservoir or to divert water to a run-of-river
hydropower plant. A reservoir and operation of the dam can affect the
natural water habitat due to changes in water temperatures, chemistry, flow
characteristics, and silt loads, all of which can lead to significant changes in
the ecology and physical characteristics of the river upstream and
downstream. Construction of reservoirs may cause natural areas, farms, and
archeological sites to be covered and force populations to relocate. Hydro
turbines kill and injure some of the fish that pass through the turbine
although there are ways to reduce that effect. In areas where salmon must
travel upstream to spawn, such as along the Columbia River in Washington
and Oregon, the dams get in the way. This problem can be partially
alleviated by using “fish ladders” that help the salmon get up the dams.
Carbon dioxide and methane may also form in reservoirs where water is
more stagnant and be emitted to the atmosphere. The exact amount of
greenhouse gases produced from hydropower plant reservoirs is
uncertain. If the reservoirs are located in tropical and temperate regions,
including the United States, those emissions may be equal to or greater than
the greenhouse effect of the carbon dioxide emissions from an equivalent
amount of electricity generated with fossil fuels (EIA, 2011).
Municipal Solid Waste
Waste to energy processes are gaining renewed interest as they can solve
two problems at once — disposal of waste as landfill capacity decreases and
production of energy from a renewable resource. Many of the
environmental impacts are similar to those of a coal plant — air pollution,
ash generation, etc. Since the fuel source is less standardized than coal and
hazardous materials may be present in municipal solid waste (MSW), or
garbage, incinerators and waste-to-energy power plants need to clean the
stack gases of harmful materials. The U.S. EPA regulates these plants very
strictly and requires anti-pollution devices to be installed. Also, while
incinerating at high temperature many of the toxic chemicals may break
down into less harmful compounds.
The ash from these plants may contain high concentrations of various
metals that were present in the original waste. If ash is clean enough it can
be “recycled” as an MSW landfill cover or to build roads, cement block and
artificial reefs.
Biomass
Biomass is derived from plants. Examples include lumber mill sawdust,
paper mill sludge, yard waste, or oat hulls from an oatmeal processing
plant. A major challenge of biomass is determining if it is really a more
sustainable option. It often takes energy to make energy and biomass is one
example where the processing to make it may not be offset by the energy it
produces. For example, biomass combustion may increase or decrease
emission of air pollutants depending on the type of biomass and the types of
fuels or energy sources that it replaces. Biomass reduces the demand for
fossil fuels, but when the plants that are the sources of biomass are grown, a
nearly equivalent amount of CO> is captured through photosynthesis, thus it
recycles the carbon. If these materials are grown and harvested in a
sustainable way there can be no net increase in CO, emissions. Each type of
biomass must be evaluated for its full life-cycle impact in order to
determine if it is really advancing sustainability and reducing environmental
impacts.
Woodchips Photograph shows a pile of woodchips, which are a type
of biomass. Source: Ulrichulrich
Solid Biomass: Burning Wood
Using wood, and charcoal made from wood, for heating and cooking can
replace fossil fuels and may result in lower CO, emissions. If wood is
harvested from forests or woodlots that have to be thinned or from urban
trees that fall down or needed be cut down anyway, then using it for
biomass does not impact those ecosystems. However, wood smoke contains
harmful pollutants like carbon monoxide and particulate matter. For home
heating, it is most efficient and least polluting when using a modern wood
stove or fireplace insert that are designed to release small amounts of
particulates. However, in places where wood and charcoal are major
cooking and heating fuels such as in undeveloped countries, the wood may
be harvested faster than trees can grow resulting in deforestation.
Biomass is also being used on a larger scale, where there are small power
plants. For instance, Colgate College has had a wood-burning boiler since
the mid-1980’s and in one year it processed approximately 20,000 tons of
locally and sustainably harvested wood chips, the equivalent of 1.17 million
gallons (4.43 million liters) of fuel oil, avoiding 13,757 tons of emissions,
and saving the university over $1.8 million in heating costs. The
University’s steam-generating wood-burning facility now satisfies more
than 75 percent of the campus's heat and domestic hot water needs. For
more information about this, click here
Gaseous Biomass: Landfill Gas or Biogas
Landfill gas and biogas is a sort of man-made “biogenic” gas as discussed
above. Methane and carbon dioxide are formed as a result of biological
processes in sewage treatment plants, waste landfills, anaerobic
composting, and livestock manure management systems. This gas is
captured, and burned to produce heat or electricity usually for on-site
generation. The electricity may replace electricity produced by burning
fossil fuels and result in a net reduction in CO» emissions. The only
environmental impacts are from the construction of the plant itself, similar
to that of a natural gas plant.
Liquid Biofuels: Ethanol and Biodiesel
Biofuels may be considered to be carbon-neutral because the plants that are
used to make them (such as corn and sugarcane for ethanol, and soy beans
and palm oil trees for biodiesel) absorb CO, as they grow and may offset
the CO, produced when biofuels are made and bummed. Calculating the net
energy or CO» generated or reduced in the process of producing the biofuel
is crucial to determining its environmental impact.
Even if the environmental impact is net positive, the economic and social
effects of growing plants for fuels need to be considered, since the land,
fertilizers, and energy used to grow biofuel crops could be used to grow
food crops instead. The competition of land for fuel vs. food can increase
the price of food, which has a negative effect on society. It could also
decrease the food supply increasing malnutrition and starvation globally.
Biofuels may be derived from parts of plants not used for food (cellulosic
biomass) thus reducing that impact. Cellulosic ethanol feedstock includes
native prairie grasses, fast growing trees, sawdust, and even waste paper.
Also, in some parts of the world, large areas of natural vegetation and
forests have been cut down to grow sugar cane for ethanol and soybeans
and palm-oil trees to make biodiesel. This is not sustainable land use.
Biofuels typically replace petroleum and are used to power vehicles.
Although ethanol has higher octane and ethanol-gasoline mixtures burn
cleaner than pure gasoline, they also are more volatile and thus have higher
"evaporative emissions" from fuel tanks and dispensing equipment. These
emissions contribute to the formation of harmful, ground level ozone and
smog. Gasoline requires extra processing to reduce evaporative emissions
before it is blended with ethanol.
Biodiesel can be made from used vegetable oil and has been produced on a
very local basis. Compared to petroleum diesel, biodiesel combustion
produces less sulfur oxides, particulate matter, carbon monoxide, and
unburned and other hydrocarbons, but more nitrogen oxide.
Endless Sources of Energy: Earth, Wind, and Sun
Geothermal Energy
Five percent of the United States’ renewable energy portfolio is from
geothermal energy (see Figure U.S. Energy Consumption by Energy
Source, 2009). The subsurface temperature of the earth provides an endless
energy resource. The environmental impact of geothermal energy depends
on how it is being used. Direct use and heating applications have almost no
negative impact on the environment.
Installing a Geothermal Pipe
System Drilling to install geothermal
ground source pipe system. Source:
Office of Sustainability, UIC
Geothermal power plants do not burn fuel to generate electricity so their
emission levels are very low. They release less than one percent of the
carbon dioxide emissions of a fossil fuel plant. Geothermal plants use
scrubber systems to clean the air of hydrogen sulfide that is naturally found
in the steam and hot water. They emit 97 percent less acid rain-causing
sulfur compounds than are emitted by fossil fuel plants. After the steam and
water from a geothermal reservoir have been used, they are injected back
into the earth.
Geothermal ground source systems utilize a heat-exchange system that runs
in the subsurface about 20 feet (5 meters) below the surface where the
ground is at a constant temperature. The system uses the earth as a heat
source (in the winter) or a heat sink (in the summer). This reduces the
energy consumption requires to generate heat from gas, steam, hot water,
and chiller and conventional electric air-conditioning systems. See more in
Chapter Sustainable Energy Systems.
Solar Energy
Solar power has minimal impact on the environment, depending on where it
is placed. In 2009, one percent of the renewable energy generated in the
United States was from solar power (1646 MW) out of the eight percent of
the total electricity generation that was from renewable sources. The
manufacturing of photovoltaic (PV) cells generates some hazardous waste
from the chemicals and solvents used in processing. Often solar arrays are
placed on roofs of buildings or over parking lots or integrated into
construction in other ways. However, large systems may be placed on land
and particularly in deserts where those fragile ecosystems could be
damaged if care is not taken. Some solar thermal systems use potentially
hazardous fluids (to transfer heat) that require proper handling and disposal.
Concentrated solar systems may need to be cleaned regularly with water,
which is also needed for cooling the turbine-generator. Using water from
underground wells may affect the ecosystem in some arid locations.
Rooftop Solar Installations Rooftop
solar installation on Douglas Hall at
the University of Illinois at Chicago
has no effect on land resources, while
producing electricity with zero
emissions. Source: Office of
Sustainability, VIC
Wind
Wind is a renewable energy source that is clean and has very few
environmental challenges. Wind turbines are becoming a more prominent
sight across the United States, even in regions that are considered to have
less wind potential. Wind turbines (often called windmills) do not release
emissions that pollute the air or water (with rare exceptions), and they do
not require water for cooling. The U.S. wind industry had 40,181 MW of
wind power capacity installed at the end of 2010, with 5,116 MW installed
in 2010 alone, providing more than 20 percent of installed wind power
around the globe. According to the American Wind Energy Association,
over 35 percent of all new electrical generating capacity in the United
States since 2006 was due to wind, surpassed only by natural gas.
Twin Groves Wind Farm, Illinois Wind power is
becoming a more popular source of energy in the
United States. Source: Office of Sustainability,
IG
Since a wind turbine has a small physical footprint relative to the amount of
electricity it produces, many wind farms are located on crop, pasture, and
forest land. They contribute to economic sustainability by providing extra
income to farmers and ranchers, allowing them to stay in business and keep
their property from being developed for other uses. For example, energy
can be produced by installing wind turbines in the Appalachian mountains
of the United States instead of engaging in mountain top removal for coal
mining. Off shore wind turbines on lakes or the ocean may have smaller
environmental impacts than turbines on land.
Wind turbines do have a few environmental challenges. There are aesthetic
concerns to some people when they see them on the landscape. A few wind
turbines have caught on fire, and some have leaked lubricating fluids,
though this is relatively rare. Some people do not like the sound that wind
turbine blades make. Listen to one here and see what you think.
Turbines have been found to cause bird and bat deaths particularly if they
are located along their migratory path. This is of particular concern if these
are threatened or endangered species. There are ways to mitigate that
impact and it is currently being researched.
There are some small impacts from the construction of wind projects or
farms, such as the construction of service roads, the production of the
turbines themselves, and the concrete for the foundations. However, overall
life cycle analysis has found that turbines make much more energy than the
amount used to make and install them.
Summary
We derive our energy from a multitude of resources that have varying
environmental challenges related to air and water pollution, land use,
carbon dioxide emissions, resource extraction and supply, as well as related
safety and health issues. A diversity of resources can help maintain political
and economic independence for the United States. Renewable energy
sources have lower environmental impact and can provide local energy
resources. Each resource needs to be evaluated within the sustainability
paradigm. In the near future, we can expect the interim use of more difficult
and environmentally-challenging extraction methods to provide fossil fuels
until the growth and development of renewable and clean energy sources
will be able to meet our energy demands.
Review Questions
Exercise:
Problem:
Describe three major environmental challenges for fossil fuels in
general or one in particular.
Exercise:
Problem:
What are the compelling reasons to continue using coal in spite of its
challenges?
Exercise:
Problem:
Rate the following electricity sources for their contribution to climate
change from most to least: biomass, coal, solar, wind, nuclear, natural
gas, oil, geothermal, hydroelectric, MSW. Is there any compelling
reason not to use any of the carbon neutral (no net carbon emissions)
sources?
Exercise:
Problem:
Describe the environmental and social concerns with regard to
biofuels.
Resources
To learn more about global energy issues, visit the International Energy
Agency website.
To learn more about United States and international energy issues, visit the
U.S. Energy Information Administration website.
To learn more about the U.S. Nuclear Regulatory Commission, please click
here.
Learn about your clean energy options here.
References
American Wind Energy Association. (2011). Industry Statistics. Retrieved
September 6, 2011 from
http://www.awea.org/learnabout/industry_stats/index.cfm
Epstein, P.R., Buonocare, J.J, Eckerle, K., Hendryx, M., Stout III, B.M.,
Heinberg, R., et al. (2011). Full cost accounting for the life cycle of coal.
Annals of the New York Academy of Sciences, 1219, 73-98. Retrieved May
17, 2011 from http://mlui.org/downloads/CoalExternalitiesHarvard02-17-
11.pdft
U.S. Energy Information Administration. (2011). Hydropower generators
produce clean electricity, but hydropower does have environmental impacts.
Retrieved September 6, 2011 from
http://www.eia. gov/energyexplained/index.cfm?
page=hydropower_ environment
Wood, J.H., Long, G.R, & Morehouse, D.F. (2004). Long-term world oil
supply scenarios: The future is neither as bleak or rosy as some assert.
Energy Information Administration. Retrieved May 17, 2011 from
http://www.eia.doe.gov/pub/oil gas/petroleum/feature_articles/2004/worldo
ilsupply/oilsupply04.html
Glossary
biodiesel
A fuel usually made from soybean, canola, or other vegetable oils;
animal fats; and recycled grease and oils. It can serve as a substitute
for conventional diesel or distillate fuel.
biofuels
Liquid fuels and blending components produced from biomass
materials, used primarily in combination with transportation fuels,
such as gasoline.
biomass
Organic, non-fossil material of biological origin that is renewable
because it can be quickly re-grown, taking up the carbon that is
released when it is burned.
geothermal energy
Hot water or steam extracted from geothermal reservoirs in the earth's
crust. Water or steam extracted from geothermal reservoirs can be used
for geothermal heat pumps, water heating, or electricity generation.
Geothermal heat or cooling may also come from ground source heat
exchange taking advantage of the constant temperature in the ground
below the surface.
geothermal plant
A power plant in which the prime mover is a steam turbine. The
turbine is driven either by steam produced from hot water or by natural
steam that heat source is found in rock.
non-renewable fuels
Fuels that will be used up, irreplaceable.
photovoltaic cells
An electronic device consisting of layers of semiconductor materials
that are produced to form adjacent layers of materials with different
electronic characteristics and electrical contacts and being capable of
converting incident light directly into electricity (direct current).
radioactive half-lives
The amount of time necessary to decrease the radioactivity of
radioactive material to one-half the original level.
renewable fuels
Fuels that are never exhausted or can be replaced.
Case Study: Greenhouse Gases and Climate Change
In this module, two case studies provide examples of climate action plans —
one for a city (Chicago) and one for an institution (the University of Illinois
at Chicago).
Introduction
If increased greenhouse gas emissions from human activity are causing
climate change, then how do we reduce those emissions? Whether dictated
by an international, national, or local regulation or a voluntary agreement,
plans are needed to move to a low-carbon economy. In the absence of
federal regulation, cities, states, government institutions, and colleges and
universities, have all taken climate action initiatives. This case study
provides two examples of climate action plans — one for a city (Chicago)
and one for an institution (the University of Illinois at Chicago).
Chicago’s Climate Action Plan
Urban areas produce a lot of waste. In fact, 75 percent of all greenhouse gas
emissions are generated in urban areas. Therefore, it is important for cities
to develop plans to address environmental issues. The Chicago Climate
Action Plan (Chicago CAP) is one such example. The mid-term goal of this
plan is a 25 percent reduction in greenhouse gas emissions by 2020 and
final goal is 80 percent reduction below 1990 GHG levels by the year 2050.
The Chicago CAP outlines several benefits of a climate action plan. The
first would obviously be the reduction of the effects of climate change.
Under a higher emissions scenario as per the Intergovernmental Panel on
Climate Change (IPCC), it is predicted that the number of 100 degree
Fahrenheit days per year would increase to 31, under the lower emissions
scenario it would only be eight. Established by the United Nations
Environment Programme (UNEP), the IPCC is the leading international
body that assesses climate change through the contributions of thousands of
scientists.
Second, there is an economic benefit derived from increased efficiencies
that reduce energy and water consumption. Third, local governments and
agencies have great influence over their city’s greenhouse gas emissions
and can enhance energy efficiency of buildings through codes and
ordinances so they play a key role in climate action at all governmental
levels. Finally, reducing our dependence on fossil fuels helps the United
States achieve energy independence.
Designing a Climate Action Plan
Millions of
metric fons
(MMTCO,e)
Percent 40
36.2
reduction of | 223MMICO,< 34.7 MMTCO,e
MMTCO,e Emissions level MMTCO,e
farting point =
Siang poiml ee 2005 2008 24.2 MMICO,¢
d 1990:— .. Reduce
issions
level by 25%
Chicago Greenhouse Gas Emissions and Reduction Goals Figure
illustrates the emissions calculated for Chicago through 2005. Source:
City of Chicago, Chicago Climate Action Plan
A good climate action plan includes reporting of greenhouse gas emissions,
as far back as there is data, preferably to 1990. Figure Chicago
Greenhouse Gas Emissions and Reduction Goals depicts the emissions
calculated for Chicago through 2005. From that point there is an estimate
(the dotted line) of a further increase before the reductions become evident
and the goals portrayed can be obtained. The plan was released in
September 2008 and provides a roadmap of five strategies with 35 actions
to reduce greenhouse gas emissions (GHG) and adapt to climate change.
The strategies are shown in Table Alignment of the Chicago and UIC
Climate Action Plans. Figure Sources of the Chicago CAP Emission
Reductions by Strategy identifies the proportion of emissions reductions
from the various strategies.
@ Energy efficient buildings
@ Clean & renewable energy
sources
= Improved transportation
options
@ Reduced waste &
industrial pollution
Graph shows the sources of the Chicago CAP emission
reductions by strategy. Source: C. Klein-Banai using data
from City of Chicago, Chicago Climate Action Plan.
In 2010 CCAP put out a progress report wherein progress is measured by
the many small steps that are being taken to implement the plan. It is not
translated exactly to emissions reductions but reports on progress for each
step such as the number of residential units that have been retrofitted for
energy efficiency, the number of appliances traded in, the increase in the
number of rides on public transit, and the amount of water conserved daily.
University Climate Action Plan
Several factors caused a major Chicago university to develop a climate
action plan. As part of the American College and University Presidents’
Climate Commitment (ACUPCC), nearly 670 presidents have signed a
commitment to inventory their greenhouse gases, publicly report it, and to
develop a climate action plan. Part of the Chicago CAP is to engage
businesses and organizations within the city in climate action planning. In
order to be a better steward of the environment, the University of Illinois at
Chicago (UIC) developed a climate action plan. The goals are similar to
Chicago’s: a 40 percent GHG emissions reduction by 2030 and at least 80
percent by 2050, using a 2004 baseline. The strategies align with those of
the city in which the campus resides (see Table Alignment of the Chicago
and UIC Climate Action Plans). UIC’s greenhouse gas reports are also
made publically available on the ACUPCC reporting site. Figure UIC’s
Projected Emissions Reductions displays UIC’s calculated emissions
inventory (in red) and then the predicted increases for growth if activities
continue in a “business as usual (BAU)” approach. The triangular wedges
below represent emissions reductions through a variety of strategies, similar
to those of the wedge approach that Professors Sokolow and Pacala
proposed. Those strategies are displayed in Table Alignment of the
Chicago and UIC Climate Action Plans, alongside Chicago’s for
comparative purposes.
350,000
300,000
250,000
200,000 es Energy Conservation
Mumm Energy Efficiency
mum Onsite Renewables
150,000
ee Purchased Renewable Electricity
=a Commuting
100,000 Biogas
Metric Tons CO, Equivalent (MTCO,e)
Me \Vaste
FY2004 Baseline
50,000
Current
BAU
0 T T T T T T T T T T r T 1
2004 2006 2008 2010 2012 2014 2016 2018 2020 2022 2024 2026 2028 2030
Fiscal Year
UIC’s Projected Emissions Reductions Projected emissions
reductions from 2004 to 2030. Where BAU stands for Business as
Usual, what would happen if no action were taken? Source: UIC
Climate Action Plan, figure 6.
The UIC CAP also has major strategy categories that are similar to
Chicago’s and within each strategy there are a number of recommended
actions. Progress on this plan will be monitored both by reporting emissions
at least every two years to the ACUPCC and by tracking individual actions
and reporting to the campus community.
CHICAGO CAP
Energy Efficient
Buildings
Retrofit commercial and
industrial buildings
Retrofit residential
buildings
Trade in appliances
Conserve water
Update City energy code
Establish new guidelines
for renovations
Cool with trees and green
roofs
Take easy steps
Clean & Renewable
Energy Sources
Upgrade power plants
Improve power plant
efficiency
Build renewable
electricity
UIC CAP
Energy Efficiency and
Conservation
Retrofit buildings
Energy performance contracting
Monitoring and maintenance
Water conservation
Establish green building standards
Green roofs/reflective roofs
Energy conservation by campus
community
Clean and Renewable Energy
Modify power plants
Purchase electricity from a renewable
electricity provider
Build renewable electricity
Increase distributed
generation
Promote household
renewable power
Improved
Transportation Options
Invest more in transit
Expand transit incentives
Promote transit-oriented
development
Make walking and biking
easier
Car share and car pool
Improve fleet efficiency
Achieve higher fuel
efficiency standards
Switch to cleaner fuels
Support intercity rail
Improve freight
movement
Reduced Waste &
Industrial Pollution
Geothermal heating and cooling
Improved Transportation Options
Expand transit incentives
Make walking and biking easier
Car sharing/car pool program
Continue to improve fleet efficiency
Reduce business travel (web
conferencing)
Anti-Idling regulations/guidelines
Recycling and Waste Management
Reduce, reuse and recycle
Shift to alternative
refrigerants
Capture stormwater on
site
Preparation
(Adaptation)
Manage heat
Protect air quality
Manage stormwater
Implement green urban
design
Preserve plants and trees
Pursue innovative cooling
Establishing recycling goals
Composting
Sustainable food purchases & use of
biodegradable packaging
Collecting and converting vegetable
oil
Develop a user-friendly property
management system
Expand the waste minimization
program
Recycle construction debris
Purchasing policies
Improved Grounds Operations
Capture stormwater on site
Use native species
Reduce/eliminate irrigation
Integrated pest management
Tree care plan
Engage the public Education, Research and Public
Engagement
Engage businesses Employment Strategies
Plan for the future Telecommuting
Flextime
Childcare center
Public Engagement
Alignment of the Chicago and UIC Climate Action Plans Source: C.
Klein-Banai using data from Chicago Climate Action Plant and UIC
Climate Action Plan
Conclusion
There is no one approach that will effectively reduce greenhouse gas
emissions. Climate action plans are helpful tools to represent strategies to
reduce emissions. Governmental entities such as nations, states, and cities
can develop plans, as can institutions and businesses. It is important that
there be an alignment of plans when they intersect, such as a city anda
university that resides within it.
Electricity
In this module, the following topics are covered: 1) growth of electricity as
a clean, versatile, switchable energy carrier; 2) components of the electricity
grid — generation, delivery, use, and 3) challenges to the modern electricity
grid
Learning Objectives
After reading this module, students should be able to
¢ outline the growth of electricity as a clean, versatile, switchable energy
carrier
e understand the components of the electricity grid — generation,
delivery, use
e understand the challenges to the modern electricity grid — capacity,
reliability, accommodating renewables
Introduction
Over the past century and a half electricity has emerged as a popular and
versatile energy carrier. Communication was an early widespread use for
electricity following the introduction of the telegraph in the 1840s. In the
1870s and 1880s electric motors and lights joined the telegraph as practical
electrical devices, and in the 1890s electricity distribution systems, the
forerunners of today's electricity grid, began to appear. The telegraph
became wireless with the invention of radio, demonstrated in the laboratory
in the 1880s and for transatlantic communication in 1901. Today, electricity
is exploited not only for its diverse end uses such as lighting, motion,
refrigeration, communication and computation, but also as a primary carrier
of energy. Electricity is one of two backbones of the modern energy system
(liquid transportation fuels are the other), carrying high density energy over
short and long distances for diverse uses. In 2009, electricity consumed the
largest share of the United States’ primary energy, 38 percent, with
transportation a close second at 37 percent (ELA Annual Energy Review,
2009). These two sectors also accounted for the largest shares of U.S.
carbon emissions, 38 percent for electricity and 33 percent for
transportation (EIA Annual Energy Review, 2009). Figure United States
Electricity Net Generation Since 1949 and Uses shows the growth of
electricity as an energy carrier since 1949 and the growing range of its uses.
United States
Electricity Net Generation
1950 1960 1970 1980 1990 2000 2010
United States Electricity Net Generation Since 1949 and Uses The
growth of United States electricity generation since 1949 and some of
its uses. Source: G. Crabtree using data from EJA Annual Energy
Figure Electricity Energy Chain shows the electricity energy chain from
generation to use. By far most electricity is generated by combustion of
fossil fuels to turn steam or gas turbines. This is the least efficient step in
the energy chain, converting only 36 percent of the chemical energy in the
fuel to electric energy, when averaged over the present gas and coal
generation mix. It also produces all the carbon emissions of the electricity
chain. Beyond production, electricity is a remarkably clean and efficient
carrier. Conversion from rotary motion of the turbine and generator to
electricity, the delivery of electricity through the power grid, and the
conversion to motion in motors for use in industry, transportation and
refrigeration can be more than 90 percent efficient. None of these steps
produces greenhouse gas emissions. It is the post-production versatility,
cleanliness, and efficiency of electricity that make it a prime energy carrier
for the future. Electricity generation, based on relatively plentiful domestic
coal and gas, is free of immediate fuel security concerns. The advent of
electric cars promises to increase electricity demand and reduce dependency
on foreign oil, while the growth of renewable wind and solar generation
reduces carbon emissions. The primary sustainability challenges for
electricity as an energy carrier are at the production step: efficiency and
emission of carbon dioxide and toxins.
Crm) CG) GED —
~~ So \ CSD
en ean) — Cop
ieee via a Cindustry)
‘> i ED
38% of |
clean, efficient,
ra
—
iio
primary energy
38% of
carbon emissions
low carbon energy
Electricity Energy Chain Graph shows the electricity energy chain
from generation to use. Source: G. Crabtree
The Electricity Grid: Capacity and Reliability
Beyond production, electricity faces challenges of capacity, reliability, and
implementing storage and transmission required to accommodate the
remoteness and variability of renewables. The largest capacity challenges
are in urban areas, where 79 percent of the United States and 50 percent of
the world population live. The high population density of urban areas
requires a correspondingly high energy and electric power density. In the
United States, 33 percent of electric power is used in the top 22 metro areas,
and electricity demand is projected to grow 31 percent by 2035 (Annual
Energy Outlook, 2011). This creates an "urban power bottleneck" where
underground cables become saturated, hampering economic growth and the
efficiencies of scale in transportation, energy use and greenhouse gas
emission that come with high population density (Qwen, 2009). Saturation
of existing cable infrastructure requires installation of substantial new
capacity, an expensive proposition for digging new underground cable
tunnels.
Superconducting underground cables with five times the power delivery
capacity of conventional copper offer an innovative alternative (see Figure
Superconducting Underground Cables). Unlike conventional cables,
superconducting cables emit no heat or electromagnetic radiation,
eliminating interference with other underground energy and communication
infrastructure. Replacing conventional with superconducting cables in
urban areas dramatically increases capacity while avoiding the construction
expense of additional underground infrastructure.
Superconducting Underground Cables The
superconducting wires on the right carry the
Same current as the conventional copper wires
on the left. Superconducting cable wound from
these wires carries up to five times the current
of conventional copper cables. Source:
Courtesy, American Superconductor
Corporation
The reliability of the electricity grid presents a second challenge. The
United States’ grid has grown continuously from origins in the early 20th
Century; much of its infrastructure is based on technology and design
philosophy dating from the 1950s and 1960s, when the major challenge was
extending electrification to new rural and urban areas. Outside urban areas,
the grid is mainly above ground, exposing it to weather and temperature
extremes that cause most power outages. The response to outages is
frustratingly slow and traditional — utilities are often first alerted to outages
by telephoned customer complaints, and response requires sending crews to
identify and repair damage, much the same as we did 50 years ago. The
United States’ grid reliability is significantly lower than for newer grids in
Europe and Japan, where the typical customer experiences ten to 20 times
less outage time than in the United States. Reliability is especially
important in the digital age, when an interruption of even a fraction of a
cycle can shut down a digitally controlled data center or fabrication line,
requiring hours or days to restart.
Reliability issues can be addressed by implementing a smart grid with two-
way communication between utility companies and customers that
continuously monitors power delivery, the operational state of the delivery
system, and implements demand response measures adjusting power
delivered to individual customers in accordance with a previously
established unique customer protocol. Such a system requires installing
digital sensors that monitor power flows in the delivery system, digital
decision and control technology and digital communication capability like
that already standard for communication via the Internet. For customers
with on-site solar generation capability, the smart grid would monitor and
control selling excess power from the customer to the utility.
Figure Smart Grid illustrates the two-way communication features of the
smart grid. The conventional grid in the upper panel sends power one way,
from the generating station to the customer, recording how much power
leaves the generator and arrives at the customer. In the smart grid, the
power flow is continuously monitored, not only at the generator and the
customer, but also at each connection point in between. Information on the
real time power flow is sent over the Internet or another special network to
the utility and to the customer, allowing real time decisions on adding
generation to meet changes in load, opening circuit breakers to reroute
power in case of an outage, reducing power delivered to the customer
during peak periods to avoid outages (often called "demand response"), and
tracking reverse power flows for customers with their own solar or other
generation capacity. The conventional power grid was designed in the
middle of the last century to meet the simple need of delivering power in
one direction. Incorporating modern Internet-style communications and
control features could bring the electricity grid to a qualitatively new level
of capability and performance required to accommodate local generation
and deliver higher reliability.
Electrical Infrastructure
“Intelligence ” Infrastructure L we) ae
Ab
ha obb a
Smart Grid The addition of real-time monitoring and
communicating capability like that used on the Internet would add
‘smart’ operation of the electricity grid. Source: National Institute of
Standards and Technology
Smart components incorporated throughout the grid would be able to detect
overload currents and open breakers to interrupt them quickly and
automatically to avoid unnecessary damage and triggering a domino effect
cascade of outages over wide areas as happened in the Northeast Blackout
of 2003. For maximum effectiveness, such smart systems require fast
automatic response on millisecond time scales commensurate with the cycle
time of the grid. Even simple digital communication meets this
requirement, but many of the grid components themselves cannot respond
so quickly. Conventional mechanical circuit breakers, for example, take
many seconds to open and much longer to close. Such long times increase
the risk of dangerous overload currents damaging the grid or propagating
cascades. Along with digital communications, new breaker technology,
such as that based on fast, self-healing superconducting fault current
limiters, is needed to bring power grid operation into the moder era.
Integrating Renewable Electricity on the Grid
Accommodating renewable electricity generation by wind and solar plants
is among the most urgent challenges facing the grid. Leadership in
promoting renewable electricity has moved from the federal to the state
governments, many of which have legislated Renewable Portfolio
Standards (RPS) that require 20 percent of state electricity generation to be
renewable by 2020. 30 states and the District of Columbia have such
requirements, the most aggressive being California with 33 percent
renewable electricity required by 2020 and New York with 30 percent by
2015. To put this legal requirement in perspective, wind and solar now
account for about 1.6 percent of U.S. electricity production; approximately
a factor of ten short of the RPS requirements. (Crabtree & Misewich, 2010).
Renewable Variability
The grid faces major challenges to accommodate the variability of wind and
solar electricity. Without significant storage capacity, the grid must
precisely balance generation to demand in real time. At present, the
variability of demand controls the balancing process: demand varies by as
much as a factor of two from night to day as people go through their daily
routines. This predictable variability is accommodated by switching reserve
generation sources in and out in response to demand variations. With
renewable generation, variation can be up to 70 percent for solar
electricity due to passing clouds and 100 percent for wind due to calm days,
much larger than the variability of demand. At the present level of 1.6
percent wind and solar penetration, the relatively small variation in
generation can be accommodated by switching in and out conventional
resources to make up for wind and solar fluctuations. At the 20 percent
penetration required by state Renewable Portfolio Standards,
accommodating the variation in generation requires a significant increase in
the conventional reserve capacity. At high penetration levels, each addition
of wind or solar capacity requires a nearly equal addition of conventional
Capacity to provide generation when the renewables are quiescent. This
double installation to insure reliability increases the cost of renewable
electricity and reduces its effectiveness in lowering greenhouse gas
emissions.
A major complication of renewable variation is its unpredictability. Unlike
demand variability, which is reliably high in the afternoon and low at night,
renewable generation depends on weather and does not follow any pattern.
Anticipating weather-driven wind and solar generation variability requires
more sophisticated forecasts with higher accuracy and greater confidence
levels than are now available. Because today's forecasts often miss the
actual performance target, additional conventional reserves must be held at
the ready to cover the risk of inaccuracies, adding another increase to the
cost of renewable electricity.
Storing Electricity
Storage of renewable electricity offers a viable route to meeting the variable
generation challenge. Grid electricity storage encompasses many more
options than portable electricity storage required for electric cars. Unlike
vehicle storage, grid storage can occupy a large footprint with little or no
restriction on weight or volume. Grid storage can be housed in a controlled
environment, eliminating large temperature and humidity variations that
affect performance. Grid storage must have much higher capacity than
vehicle storage, of order 150 MWh for a wind farm versus 20-50 kWh for
a vehicle. Because of these differences, the research strategy for grid and
vehicle energy storage is very different. To date, much more attention has
been paid to meeting vehicle electricity storage requirements than grid
storage requirements.
There are many options for grid storage. Pumped hydroelectric storage,
illustrated in Figure Pumped Hydroelectric Storage, is an established
technology appropriate for regions with high and low elevation water
resources. Compressed Air Energy Storage (CAES) is a compressed air
equivalent of pumped hydro that uses excess electricity to pump air under
pressure into underground geologic formations for later release to drive
generators. This option has been demonstrated in Huntorf, Germany and in
Mcintosh, Alabama. High temperature sodium-sulfur batteries operating at
300 °C have high energy density, projected long cycle life, and high round
trip efficiency; they are the most mature of the battery technologies
suggested for the grid. Flow batteries are an attractive and relatively
unexplored option, where energy is stored in the high charge state of a
liquid electrolyte and removed by electrochemical conversion to a low
charge state. Each flow battery requires an electrolyte with a high and low
charge state and chemical reaction that takes one into the other. There are
many such electrolytes and chemical reactions, of which only a few have
been explored, leaving a host of promising opportunities for the future. The
energy storage capacity depends only on the size of the storage tank, which
can be designed fully independently of the power capacity that depends on
the size of the electrochemical reactor. Sodium sulfur and flow batteries
store electric charge and can be used at any place in the electricity grid. In
contrast, thermal storage applies only to concentrating solar power
technologies, where mirrors focus solar radiation to heat a working fluid
that drives a conventional turbine and generator. In these systems, heat
energy can be stored as a molten salt in a highly insulated enclosure for
hours or days, allowing solar electricity to be generated on demand after
sunset or on cloudy days. All of these options are promising and require
research and development to explore innovations, performance and cost
limits.
Pumped Hydroelectric Storage Upper
storage reservoir for pumped hydroelectric
storage, an established technology for
storing large amounts of grid electricity.
Source: Ongrys via Wikimedia Commons
How to Transmit Electricity Over Long Distances
The final challenge for accommodating renewables is long distance
transmission. As Figure Renewable Resource Location vs. Demand
Location shows, the largest wind resources, located at mid-continent, and
the largest solar resources, in the southwest, are far from the population
centers east of Mississippi and on the West Coast. If these resources are to
be used, higher capacity long distance transmission must be developed to
bring the renewable electricity to market. Although such long distance
delivery is possible where special high voltage transmission lines have been
located, the capacity and number of such lines is limited. The situation is
much like automobile transportation before the interstate highway system
was built in the 1950s. It was possible to drive coast to coast, but the
driving time was long and uncertain and the route indirect. To use
renewable electricity resources effectively, we must create a kind of
interstate highway system for electricity.
Renewable Resource Location vs. Demand Location Wind and
solar electricity resources are located far from population centers,
requiring a dramatic improvement in long-distance electricity
transmission — an "interstate highway system for electricity." Source:
Integrating Renewable Electricity on the Grid, Report of the Panel on
Summary
Electricity and liquid petroleum are the two primary energy carriers in the
United States, and in the world. Once produced, electricity is clean and
versatile making it an appealing energy carrier for the future. The
challenges facing the electricity grid are capacity, reliability, and
accommodating renewable sources such as solar and wind whose output is
variable and whose location is remote from population centers. Electricity
storage and long distance transmission are needed to accommodate these
renewable resources.
Review Questions
Exercise:
Problem:
Electricity is the fastest growing energy carrier in the world, trailed by
liquid fuels for transportation. Why is electricity more appealing than
liquid fuels?
Exercise:
Problem:
A primary challenge for the electricity grid is capacity to handle the
"urban power bottleneck" in cities and suburbs. How can
superconducting cables address urban capacity issues?
Exercise:
Problem:
Renewable wind and solar electricity is plentiful in the United States,
but they are located remotely from high population centers and their
output is variable in time. How can these two issues be addressed?
References
Crabtree, G. & Misewich, J. (Co-Chairs). (2010). Integrating Renewable
Electricity on the Grid, American Physical Society. American Physical
Society, Washington D.C. Retrieved August 12, 2011 from
http://www.aps.org/policy/reports/popa-reports/upload/integratingelec.pdf
Owen, D. (2009). Green Metropolis: Why Living Smaller, Living Closer,
And Driving Less Are the Keys to Sustainability. New York: Riverhead
Books.
U.S. Energy Information Administration. (2010). Annual Energy Review
2009. Retrieved August 12, 2011 from
http://www.eia. gov/totalenergy/data/annual/pdf/aer.pdf
Glossary
efficiency
The fraction of energy at the input that is delivered to the output of a
device. Electric motors can convert incoming electricity to rotary
motion at more than 90 percent efficiency, while gasoline engines
convert only about 25 percent of the chemical energy of the fuel to
motion of the wheels.
electricity grid
The network of wires and transformers that delivers electric power
from generation stations such as those powered by coal, natural gas,
hydroelectricity, sunlight or wind to end uses such as lighting,
transportation, refrigeration, computation or communication. The
electricity grid is conventionally divided into higher voltage
transmission lines for long distances, lower voltage distribution lines
for short distances and transformers in substations for converting the
voltage between the two categories.
kWh and MWh
Units of energy used in power engineering. kWh is one kilowatt of
power delivered for one hour, MWh is one megawatt of power
delivered for one hour.
primary energy
The energy embodied in natural resources prior to undergoing any
human-made conversions or transformations. Examples include the
chemical energy in coal or the sunlight falling on a solar cell before it
is converted to electricity, the nuclear energy in the fuel of a nuclear
reactor, or the kinetic energy of wind before it turns the blades of a
turbine.
renewable generation variability
The variation of the output of a solar or wind plant depending on
weather. Solar plants often produce only 15-20 percent of their
maximum output (also called installed capacity) because the sun shines
only during the day and passing clouds can obscure it; wind plants
produce 20-40 percent of their maximum capacity because the wind
speed varies with weather conditions, often becoming calm for days at
a time.
smart grid
The addition of sensors to monitor power flow and two-way
communication to transmit the power flow information to the utility
and the customer in real time. The addition of sensors and
communication to the grid enables several new operating modes: the
customer decide in real time to curtail his electricity use during peak
times when rates are high (known as demand-response), the utility can
identify precisely the time and place of power flow failures due to
weather or other events, and the grid can be equipped with automatic
circuit breakers (known as fault current limiters) and other protection
devices that respond immediately to power flow failures, limiting
damage to the grid and the risk of triggering a cascade of failures.
superconducting cable
An underground cable made of superconductor, which loses all
resistance to electric current at low temperature. Superconducting
cables made of second-generation coated conductors based on the
copper oxide family of superconductors discovered in 1986 are now
entering the grid. Because superconductors conduct electricity without
producing heat, they can carry up to five times more power than
conventional copper cables in the same cross-sectional area.
Fossil Fuels (Coal and Gas)
In this module, the following topics are covered: 1) contributions of coal
and gas to electricity generation and to carbon emissions, 2) the link
between electricity generation and carbon emissions, 3) the challenges of
sequestering carbon in geologic formations — chemical transformation,
migration, and longevity
Learning Objectives
After reading this module, students should be able to
¢ outline the relative contributions of coal and gas to electricity
generation and to carbon emissions
e understand the link between electricity generation and carbon
emissions
e understand the challenges of sequestering carbon in geologic
formations — chemical transformation, migration, and longevity
Introduction
At present the fossil fuels used for electricity generation are predominantly
coal (45 percent) and gas (23 percent); petroleum accounts for
approximately 1 percent (see Figure Electricity Generation by Source).
Coal electricity traces its origins to the early 20th Century, when it was the
natural fuel for steam engines given its abundance, high energy density and
low cost. Gas is a later addition to the fossil electricity mix, arriving in
significant quantities after World War II and with its greatest growth since
1990 as shown in Figure Growth of Fuels Used to Produce Electricity in
the United States (EIA Annual Energy Review, 2009). Of the two fuels,
coal emits almost twice the carbon dioxide as gas for the same heat output,
making it significantly greater contributor to global warming and climate
change.
Nuclear
Electric Power
1 7 . .
Wind, petroleum, wood, waste, geothermal, other gases, solar thermal and photovoltaic, batteries,
chemicals, hydrogen, pitch, purchased steam, sulfur, miscellaneous technologies, and non-renewable
waste (municipal solid waste from non-biogenic sources, and tire-derived fuels
?Conventional hydroelectric power and pumped storage
Note: Sum of components may not equal 100 percent due to independent rounding.
Electricity Generation by Source Chart shows U.S. electricity
generation by source. Source: U.S. Energy Information
24-
18-
12-
Quadrillion Btu
Nuclear Electric
P
6- Renewable
Energy Natural Gas
i ee
1950 1960 1970 1980 1990 2000
Growth of Fuels Used to Produce Electricity in the
United States Graph shows the growth of fuels used to
produce electricity in the United States from 1950 to
2009. Source: U.S. Energy Information Administration,
Annual Energy Review 2009, _p. 238 (Aug. 2010)
The Future of Gas and Coal
The future development of coal and gas depend on the degree of public and
regulatory concern for carbon emissions, and the relative price and supply
of the two fuels. Supplies of coal are abundant in the United States, and the
transportation chain from mines to power plants is well established by long
experience. The primary unknown factor is the degree of public and
regulatory pressure that will be placed on carbon emissions. Strong
regulatory pressure on carbon emissions would favor retirement of coal and
addition of gas power plants. This trend is reinforced by the recent dramatic
expansion of shale gas reserves in the United States due to technology
advances in horizontal drilling and hydraulic fracturing ("fracking") of
shale gas fields. Shale gas production has increased 48 percent annually in
the years 2006 — 2010, with more increases expected (EIA Annual Energy
Outlook, 2011). Greater United States production of shale gas will
gradually reduce imports and could eventually make the United States a net
exporter of natural gas.
The technique of hydraulic fracturing of shale uses high-pressure fluids to
fracture the normally hard shale deposits and release gas and oil trapped
inside the rock. To promote the flow of gas out of the rock, small particles
of solids are included in the fracturing liquids to lodge in the shale cracks
and keep them open after the liquids are depressurized. Although hydraulic
fracturing has been used since the 1940s, is technologically feasible,
economic, and proven to enhance gas an oil recovery, it faces considerable
environmental challenges. In aquifers overlying the Marcellus and Utica
shale formations of northeastern Pennsylvania and upstate New York,
methane contamination of drinking water associated with shale gas
The public reaction to these reports has been strong and negative,
prompting calls for greater transparency, scientific investigation and
regulatory control to clearly establish the safety, sustainability and public
confidence in the technique. See Module Environmental Challenges in
Energy, Carbon Dioxide, Air and Water for more on the process of
hydraulic fracturing and its associated risks.
Reservoir sizes in GtC
Fluxes and Rates in GtC yr?
Global Carbon Cycle, 1990s The global carbon cycle for the
1990s, showing the main annual fluxes in GtC yr-1: pre-
industrial ‘natural’ fluxes in black and ‘anthropogenic’ fluxes
in red. Source: Climate Change 2007: The Physical Science
Basis: Contribution of Working_Group I to the Fourth
Assessment Report of the Intergovernmental Panel on Climate
Change,_Cambridge University Press, figure 7.3
Beyond a trend from coal to gas for electricity generation, there is a need to
deal with the carbon emissions from the fossil production of electricity.
Figure Global Carbon Cycle, 1990s shows the size of these emissions
compared to natural fluxes between ocean and atmosphere and from
vegetation and land use. The anthropogenic fluxes are small by comparison,
yet have a large effect on the concentration of carbon dioxide in the
atmosphere. The reason is the step-wise dynamics of the carbon cycle. The
ultimate storage repository for carbon emissions is the deep ocean, with
abundant capacity to absorb the relatively small flux from fossil fuel
combustion. Transfer to the deep ocean, however, occurs in three steps: first
to the atmosphere, then to the shallow ocean, and finally to the deep ocean.
The bottleneck is the slow transfer of carbon dioxide from the shallow
ocean to the deep ocean, governed by the great ocean conveyor belt or
thermohaline circulation illustrated in Figure Great Ocean Conveyor
Belt. The great ocean conveyor belt takes 400 — 1000 years to complete one
cycle. While carbon dioxide waits to be transported to the deep ocean, it
saturates the shallow ocean and "backs up" in the atmosphere causing
global warming and threatening climate change. If carbon emissions are to
be captured and stored (or "sequestered") they must be trapped for
thousands of years while the atmosphere adjusts to past and future carbon
emissions (Lenton, 2006).
GreaL Ocean Conveyor, Belt
Great Ocean Conveyor Belt The great ocean conveyor belt (or
thermohaline current) sends warm surface currents from the Pacific
to Atlantic oceans and cold deep currents in the opposite direction.
The conveyor belt is responsible for transporting dissolved carbon
dioxide from the relatively small reservoir of the shallow ocean to
much larger reservoir of the deep ocean. It takes 400 - 1000 years to
complete one cycle. Source: Argonne National Laboratory
Sequestration of carbon dioxide in underground geologic formations is
one process that, in principle, has the capacity to handle fossil fuel carbon
emissions (Olajire, 2010); chemical reaction of carbon dioxide to a stable
solid form is another (Stephens & Keith, 2008). For sequestration, there are
fundamental challenges that must be understood and resolved before the
process can be implemented on a wide scale.
The chemical reactions and migration routes through the porous rocks in
which carbon dioxide is stored underground are largely unknown.
Depending on the rock environment, stable solid compounds could form
that would effectively remove the sequestered carbon dioxide from the
environment. Alternatively, it could remain as carbon dioxide or transform
to a mobile species and migrate long distances, finally finding an escape
route to the atmosphere where it could resume its contribution to
greenhouse warming or cause new environmental damage. The requirement
on long term sequestration is severe: a leak rate of 1 percent means that all
the carbon dioxide sequestered in the first year escapes in a century, a blink
of the eye on the timescale of climate change.
Summary
Coal (45 percent) and gas (23 percent) are the two primary fossil fuels for
electricity production in the United States. Coal combustion produces
nearly twice the carbon emissions of gas combustion. Increasing public
opinion and regulatory pressure to lower carbon emissions are shifting
electricity generation toward gas and away from coal. The domestic supply
of gas is increasing rapidly due to shale gas released by hydraulic
fracturing, a technology with significant potential for harmful
environmental impact. Reducing the greenhouse gas impact of electricity
production requires capturing and sequestering the carbon dioxide emitted
from power plants. Storing carbon dioxide in underground geologic
formations faces challenges of chemical transformation, migration, and
longevity.
Review Questions
Exercise:
Problem:
The United States’ electricity supply is provided primarily by coal,
natural gas, nuclear, and hydropower. How safe are these fuel supplies
from interruption by international disasters, weather events or
geopolitical tension?
Exercise:
Problem:
Natural gas reserves from shale are increasing rapidly due to increased
use of hydrofracturing technology ("fracking"). The increased
domestic resource of shale gas has the potential to provide greater
energy security at the expense of greater environmental impact. What
are the long-term costs, benefits, and outlook for tapping into domestic
shale gas reserves?
Exercise:
Problem:
Anthropogenic carbon emissions are small compared to natural
exchange between ocean and atmosphere and fluxes from vegetation
and land use. Why do anthropogenic emissions have such a large effect
on the concentration of carbon dioxide in the atmosphere?
Exercise:
Problem:
One proposal for mitigating carbon emissions is capturing and storing
them in underground geologic formations (sequestration). What
scientific, technological and policy challenges must be overcome
before sequestration can be deployed widely?
References
Lenton, T.M. (2006). Climate change to the end of the millennium. Climatic
Change, 76, 7-29. doi: 10.1007/s10584-005-9022-1
Olajire, A. (2010). CO2 capture and separation technologies for end-of-pipe
applications: A review, Energy 35, pp. 2610-2628. doi:
10.1016/j.energy.2010.02.030
Osborn, S.G., Vengosh, A., Warner, N.R., & Jackson, R.B. (2011). Methane
contamination of drinking water accompanying gas-well drilling and
hydraulic fracturing. PNAS, 108, pp. 8172-1876. doi:
10.1073/pnas.1100682108
Stephens, J.C. & Keith, D.W. (2008). Assessing geochemical carbon
management. Climatic Change, 90, 217-242. doi: 10.1007/s10584-008-
9440-y
U.S. Energy Information Administration. (2010). Annual Energy Review
2009. Retrieved August 12, 2011 from
http://www.eia. gov/totalenergy/data/annual/pdf/aer. pdf
U.S. Energy Information Administration. (2011). Annual Energy Outlook
2011. Retrieved September 2, 2011 from
Glossary
carbon sequestration
The storage of carbon dioxide underground in geologic formations
consisting of depleted oil and gas wells, unmineable coal beds, and
deep saline aquifers.
great ocean conveyor belt (or Termohaline Current)
The current spanning the Pacific, Antarctic, Indian and Atlantic
Oceans that carries warm surface water to the cold deep ocean and
takes 400-1000 years to complete one cycle.
Nuclear Energy
In this module, the following topics are presented: 1) the rapid development
of nuclear electricity and its plateau due to public concerns about safety, 2)
the dilemma nuclear electricity presents for sustainability — reduced carbon
emissions and long term storage of spent fuel, 3) the sustainable benefits
and proliferation threats of reprocessing spent nuclear fuel.
Learning Objectives
After reading this module, students should be able to
¢ outline the rapid development of nuclear electricity and its plateau due
to public concerns about safety
e understand the dilemma nuclear electricity presents for sustainability —
reduced carbon emissions and long term storage of spent fuel
e understand the sustainable benefits and proliferation threats of
reprocessing spent nuclear fuel
Introduction
From a sustainability perspective, nuclear electricity presents an interesting
dilemma. On the one hand, nuclear electricity produces no carbon
emissions, a major sustainable advantage in a world facing human induced
global warming and potential climate change. On the other hand, nuclear
electricity produces spent fuel that must be stored out of the environment
for tens or hundreds of thousands of years, it produces bomb-grade
plutonium and uranium that could be diverted by terrorists or others to
destroy cities and poison the environment, and it threatens the natural and
built environment through accidental leaks of long lived radiation.
Thoughtful scientists, policy makers and citizens must weigh the benefit of
this source of carbon free electricity against the environmental risk of
storing spent fuel for thousands or hundreds of thousands of years, the
societal risk of nuclear proliferation, and the impact of accidental releases
of radiation from operating reactors. There are very few examples of
humans having the power to permanently change the dynamics of the earth.
Global warming and climate change from carbon emissions is one example,
and radiation from the explosion of a sufficient number of nuclear weapons
is another. Nuclear electricity touches both of these opportunities, on the
positive side for reducing carbon emissions and on the negative side for the
risk of nuclear proliferation.
Debating Nuclear Energy
Nuclear electricity came on the energy scene remarkably quickly. Following
the development of nuclear technology at the end of World War II for
military ends, nuclear energy quickly acquired a new peacetime path for
inexpensive production of electricity. Eleven years after the end of World
War II, in 1956, a very short time in energy terms, the first commercial
nuclear reactor produced electricity at Calder Hall in Sellafield, England.
The number of nuclear reactors grew steadily to more than 400 by 1990,
four years after the Chernobyl disaster in 1986 and eleven years following
Three Mile Island in 1979. Since 1990, the number of operating reactors
has remained approximately flat, with new construction balancing
decommissioning, due to public and government reluctance to proceed with
nuclear electricity expansion plans. Figure Growth of Fuels Used to
Produce Electricity in the United States and Figure Nuclear Share of
United States Electricity Generation show the development and status of
nuclear power in the United States, a reflection of its worldwide growth.
25-
1960 1970 1980 1990 2000
Nuclear Share of United States Electricity
Generation The percentage of electricity generated by
nuclear power in the United States, 1957-2009.
Source: U.S. Energy Information Agency, Annual
Energy Review 2009, p. 276 (Aug. 2010)
The outcome of this debate (Ferguson, Marburger, & Farmer, 2010) will
determine whether the world experiences a nuclear renaissance that has
been in the making for several years (Grimes & Nuttall, 2010). The global
discussion has been strongly impacted by the unlikely nuclear accident in
Fukushima, Japan in March 2011. The Fukushima nuclear disaster was
caused by an earthquake and tsunami that disabled the cooling system for a
nuclear energy complex consisting of operating nuclear reactors and storage
pools for underwater storage of spent nuclear fuel ultimately causing a
partial meltdown of some of the reactor cores and release of significant
radiation. This event, 25 years after Chernobyl, reminds us that safety and
public confidence are especially important in nuclear energy; without them
expansion of nuclear energy will not happen.
Permanent
Shutdowns
* Units holding full-power operating licenses, or equivalent permission to operate, at the end
of the year.
Operating and Decommissioned Nuclear Power
Plants in the United States Graph shows the number
of operating versus decommissioned nuclear power
plants in the United States. Source: U.S. Energy
Information Agency, Annual Energy Review 2009, p.
274 (Aug. 2010)
There are two basic routes for handling the spent fuel of nuclear reactors:
once through and reprocessing (World Nuclear Association; Kazimi,
Moniz, _& Forsberg, 2010). Once through stores spent fuel following a
single pass through the reactor, first in pools at the reactor site while it cools
radioactively and thermally, then in a long-term geologic storage site, where
it must remain for hundreds of thousands of years. Reprocessing separates
the useable fraction of spent fuel and recycles it through the reactor, using a
greater fraction of its energy content for electricity production, and sends
the remaining high-level waste to permanent geologic storage. The primary
motivation for recycling is greater use of fuel resources, extracting ~ 25
percent more energy than the once through cycle. A secondary motivation
for recycling is a significant reduction of the permanent geologic storage
space (by a factor of ~ 5 or more) and time (from hundreds of thousands of
years to thousands of years). While these advantages seem natural and
appealing from a sustainability perspective, they are complicated by the risk
of theft of nuclear material from the reprocessing cycle for use in illicit
weapons production or other non-sustainable ends. At present, France, the
United Kingdom, Russia, Japan and China engage in some form of
reprocessing; the United States, Sweden and Finland do not reprocess.
Summary
Nuclear electricity offers the sustainable benefit of low carbon electricity at
the cost of storing spent fuel out of the environment for up to hundreds of
thousands of years. Nuclear energy developed in only 11 years, unusually
quickly for a major energy technology, and slowed equally quickly due to
public concerns about safety following Three Mile Island and Chernobyl.
The Fukushima reactor accident in March 2011 has raised further serious
concerns about safety; its impact on public opinion could dramatically
affect the future course of nuclear electricity. Reprocessing spent fuel offers
the advantages of higher energy efficiency and reduced spent fuel storage
requirements with the disadvantage of higher risk of weapons proliferation
through diversion of the reprocessed fuel stream.
Review Questions
Exercise:
Problem:
Nuclear electricity came on the scene remarkably quickly following
the end of World War II, and its development stagnated quickly
following the Three Mile Island and Chernoby] accidents. The
Fukushima disaster of 2011 adds a third cautionary note. What
conditions must be fulfilled if the world is to experience an expansion
of nuclear electricity, often called a nuclear renaissance?
Exercise:
Problem:
Nuclear fuel can be used once and committed to storage or reprocessed
after its initial use to recover unused nuclear fuel for re-use. What are
the arguments for and against reprocessing?
Exercise:
Problem:
Storage of spent nuclear fuel for tens to hundreds of thousands of years
is a major sustainability challenge for nuclear electricity. Further
development of the Yucca Mountain storage facility has been halted.
What are some of the alternatives for storing spent nuclear fuel going
forward?
Resources
Ferguson, C.D.,Marburger, L.E. & Farmer, J.D. (2010) A US nuclear
future? Nature, 467, 391-393. doi: 10.1038/467391a
Grimes, R.J. & Nuttall, W.J. (2010). Generating the Option of a two-stage
nuclear renaissance. Science, 329, 799-803. doi: 10.1126/science.1188928
Kazimi, M., Moniz, E.J., & Forsberg, C. (2010) The Future of the Nuclear
Fuel Cycle. MIT Energy Initiative. Retrieved May 30, 2011 from
http://web.mit.edu/mitei/research/studies/nuclear-fuel-cycle.shtml.
World Nuclear Association (2011). Processing of Used Nuclear Fuel.
Retrieved May 30, 2011 from http://www.world-
nuclear.org/info/inf69. html.
Glossary
once through
A single pass of nuclear fuel through a reactor followed by long-term
geologic storage.
reprocessing
Chemically processing spent nuclear fuel to recover the unused
portion, which is then passed through the reactor again to produce
more power. Reprocessing uses a greater fraction of the energy of the
fuel but also increases the risk of illegal diversion of nuclear material
for weapons proliferation.
Renewable Energy: Solar, Wind, Hydro and Biomass
In this module, the following topics are covered: 1) the societal motivations
for renewable energy, 2) the ultimate sources of renewable energy, 3) the
geographical distribution of renewable energy, 4) cost and public opinion as
two key barriers to the widespread deployment of renewable energy.
Learning Objectives
After reading this module, students should be able to
¢ outline the societal motivations for renewable energy
¢ understand the ultimate sources of renewable energy
¢ appreciate the geographical distribution of renewable energy
e understand cost and public opinion as two key barriers to the
widespread deployment of renewable energy
Introduction
Strong interest in renewable energy in the modern era arose in response to
the oil shocks of the 1970s, when the Organization of Petroleum Exporting
Countries (OPEC) imposed oil embargos and raised prices in pursuit of
geopolitical objectives. The shortages of oil, especially gasoline for
transportation, and the eventual rise in the price of oil by a factor of
approximately 10 from 1973 to 1981 disrupted the social and economic
operation of many developed countries and emphasized their precarious
dependence on foreign energy supplies. The reaction in the United States
was a shift away from oil and gas to plentiful domestic coal for electricity
production and the imposition of fuel economy standards for vehicles to
reduce consumption of oil for transportation. Other developed countries
without large fossil reserves, such as France and Japan, chose to emphasize
nuclear (France to the 80 percent level and Japan to 30 percent) or to
develop domestic renewable resources such as hydropower and wind
(Scandinavia), geothermal (Iceland), solar, biomass and for electricity and
heat. As oil prices collapsed in the late 1980s interest in renewables, such as
wind and solar that faced significant technical and cost barriers, declined in
many countries, while other renewables, such as hydro and biomass,
continued to experience growth.
The increasing price and volatility of oil since 1998, and the increasing
dependence of many developed countries on foreign oil (60 percent of
United States and 97 percent of Japanese oil was imported in 2008) spurred
renewed interest in renewable alternatives to ensure energy security. A new
concern, not known in previous oil crises, added further motivation: our
knowledge of the emission of greenhouse gases and their growing
contribution to global warming, and the threat of climate change. An
additional economic motivation, the high cost of foreign oil payments to
supplier countries (approximately $350 billion/year for the United States at
2011 prices), grew increasingly important as developed countries struggled
to recover from the economic recession of 2008. These energy security,
carbon emission, and climate change concerns drive significant increases in
fuel economy standards, fuel switching of transportation from uncertain and
volatile foreign oil to domestic electricity and biofuels, and production of
electricity from low carbon sources.
Physical Origin of Renewable Energy
Although renewable energy is often classified as hydro, solar, wind,
biomass, geothermal, wave and tide, all forms of renewable energy arise
from only three sources: the light of the sun, the heat of the earth’s crust,
and the gravitational attraction of the moon and sun. Sunlight provides by
far the largest contribution to renewable energy, illustrated in Figure Forms
of Renewable Energy Provided by the Sun. The sun provides the heat
that drives the weather, including the formation of high- and low-pressure
areas in the atmosphere that make wind. The sun also generates the heat
required for vaporization of ocean water that ultimately falls over land
creating rivers that drive hydropower, and the sun is the energy source for
photosynthesis, which creates biomass. Solar energy can be directly
captured for water and space heating, for driving conventional turbines that
generate electricity, and as excitation energy for electrons in
semiconductors that drive photovoltaics. The sun is also responsible for the
energy of fossil fuels, created from the organic remains of plants and sea
organisms compressed and heated in the absence of oxygen in the earth’s
crust for tens to hundreds of millions of years. The time scale for fossil fuel
regeneration, however, is too long to consider them renewable in human
terms.
Geothermal energy originates from heat rising to the surface from earth’s
molten iron core created during the formation and compression of the early
earth as well as from heat produced continuously by radioactive decay of
uranium, thorium and potassium in the earth’s crust. Tidal energy arises
from the gravitational attraction of the moon and the more distant sun on
the earth’s oceans, combined with rotation of the earth. These three sources
— sunlight, the heat trapped in earth’s core and continuously generated in its
crust, and gravitational force of the moon and sun on the oceans — account
for all renewable energy.
Forms of Renewable Energy Provided by the Sun The sun is the
ultimate source for many forms of renewable energy: wind and
running water that can be used for power generation without heat or
combustion, and photosynthesis of green plants (biomass) for
combustion to provide heat and power generation and for conversion
to biofuels (upper panels). Solar energy can be directly captured for
water and space heating in buildings, after concentration by mirrors
in large plants for utility-scale power generation by conventional
turbines, and without concentration in photovoltaic cells that
produce power without heat or combustion (lower panels). Source:
G. Crabtree using images from Linuxerist, Mor plus, Richard
Dorrell, Hernantron, BSMPS, Cachogaray, and Andy F.
As relative newcomers to energy production, renewable energy typically
operates at lower efficiency than its conventional counterparts. For
example, the best commercial solar photovoltaic modules operate at about
20 percent efficiency, compared to nearly 60 percent efficiency for the best
combined cycle natural gas turbines. Photovoltaic modules in the laboratory
operate above 40 percent efficiency but are too expensive for general use,
showing that there is ample headroom for performance improvements and
cost reductions. Wind turbines are closer to their theoretical limit of 59
percent (known as Betz’s law) often achieving 35 — 40 percent efficiency.
Biomass is notoriously inefficient, typically converting less than one
percent of incident sunlight to energy stored in the chemical bonds of its
roots, stalks and leaves. Breeding and genetic modification may improve
this poor energy efficiency, though hundreds of millions of years of
evolution since the appearance of multicelled organisms have not produced
a significant advance. Geothermal energy is already in the form of heat and
temperature gradients, so that standard techniques of thermal engineering
can be applied to improve efficiency. Wave and tidal energy, though
demonstrated in several working plants, are at early stages of development
and their technological development remains largely unexplored.
Capacity and Geographical Distribution
Although renewable energies such as wind and solar have experienced
strong growth in recent years, they still make up a small fraction of the
world’s total energy needs. Figure Renewable Energy Share of Global
Final Energy Consumption, 2008 shows the contribution of fossil, nuclear
and renewable energy to final global energy consumption in 2008. The
largest share comes from traditional biomass, mostly fuel wood gathered in
traditional societies for household cooking and heating, often without
regard for sustainable replacement. Hydropower is the next largest
contributor, an established technology that experienced significant growth
in the 20" Century. The other contributors are more recent and smaller in
contribution: water and space heating by biomass combustion or harvesting
solar and geothermal heat, biofuels derived from corn or sugar cane, and
electricity generated from wind, solar and geothermal energy. Wind and
solar electricity, despite their large capacity and significant recent growth,
still contributed less than one percent of total energy in 2008.
Renewable Energy Share of Global Final Energy Consumption,
2008 The contribution of fossil, nuclear and renewable energy to
global final energy consumption in 2008. Source: REN21. 2010.
Renewables 2010 Global Status Report (Paris: REN21 Secretariat), p.
is
The potential of renewable energy resources varies dramatically. Solar
energy is by far the most plentiful, delivered to the surface of the earth at a
rate of 120,000 Terawatts (TW), compared to the global human use of 15
TW. To put this in perspective, covering 100x100 km? of desert with 10
percent efficient solar cells would produce 0.29 TW of power, about 12
percent of the global human demand for electricity. To supply all of the
earth’s electricity needs (2.4 TW in 2007) would require 7.5 such squares,
an area about the size of Panama (0.05 percent of the earth’s total land
area). The world’s conventional oil reserves are estimated at three trillion
barrels, including all the oil that has already been recovered and that remain
for future recovery. The solar energy equivalent of these oil reserves is
delivered to the earth by the sun in 1.5 days.
The global potential for producing electricity and transportation fuels from
solar, wind and biomass is limited by geographical availability of land
suitable for generating each kind of energy (described as the geographical
potential), the technical efficiency of the conversion process (reducing the
geographical potential to the technical potential), and the economic cost of
construction and operation of the conversion technology (reducing the
technical potential to the economic potential). The degree to which the
global potential of renewable resources is actually developed depends on
many unknown factors such as the future extent of economic and
technological advancement in the developing and developed worlds, the
degree of globalization through business, intellectual and social links
among countries and regions, and the relative importance of environmental
and social agendas compared to economic and material objectives.
Scenarios evaluating the development of renewable energy resources under
various assumptions about the world’s economic, technological and social
trajectories show that solar energy has 20-50 times the potential of wind or
biomass for producing electricity, and that each separately has sufficient
potential to provide the world’s electricity needs in 2050 (de Vries, 2007)
The geographical distribution of useable renewable energy is quite uneven.
Sunlight, often thought to be relatively evenly distributed, is concentrated in
deserts where cloud cover is rare. Winds are up to 50 percent stronger and
steadier offshore than on land. Hydroelectric potential is concentrated in
mountainous regions with high rainfall and snowmelt. Biomass requires
available land that does not compete with food production, and adequate
sun and rain to support growth. Figure Renewable Electricity
Opportunities shows the geographical distribution of renewable electricity
opportunities that are likely to be economically attractive in 2050 under an
aggressive world development scenario.
id:
Electricity costs
<0.19/kWh
() None
Ge Wind
Ge PV
Biomass
GH Wind+Pv
Gi PV+Biomass
Gl Wind+Biomass.
me Al
Renewable Electricity Opportunities Map shows areas
where one or more of the wind, solar, and biomass options of
renewable electricity is estimated to be able to produce
electricity in 2050 at costs below 10 b kWh. Source: de Vries,
text must be included to the Homepage of the journal from
which you are licensing at
http://www.sciencedirect.com/science/journal/03014215/35/4.
Permission for reuse must be obtained from Elsevier.
Wind and Solar Resources in the United States
The United States has abundant renewable resources. The solar resources of
the United States, Germany and Spain are compared in Figure Solar
Resources of the United States, Spain and Germany. The solar
irradiation in the southwestern United States is exceptional, equivalent to
that of Africa and Australia, which contain the best solar resources in the
world. Much of the United States has solar irradiation as good or better than
Spain, considered the best in Europe, and much higher than Germany. The
variation in irradiation over the United States is about a factor two, quite
homogeneous compared to other renewable resources. The size of the
United States adds to its resource, making it a prime opportunity for solar
development.
Mainland
United States
ES Alaska
United States
(Alaska Not to Scale)
Hawaii
United States
[== | Hawaii USA
Spain
- BEB Germany
ee ees F [3 Mainland usa
kWh/m/Year NREL
mm
Apri 10, 2008 & Cy f S SP Sf & CS & & This map was produced by the
esis owe FF KX FX KF EF FEF HEF FS HK KH PS SF woslogeverr is
Solar Resources of the United States, Spain and Germany The
solar resources of the United States, Spain and Germany, expressed
as solar insolation averaged over the year. The geographic variation
of solar irradiation in the United States is only a factor of two, much
less than for other renewable energy sources. Source: U.S.
Department of Energy, Energy Efficiency and Renewable Energy,
2008 Solar Technologies Market Report, DOE/GO-102010-2867
(January, 2010), p52.
The wind resource of the United States, while abundant, is less
homogeneous. Strong winds require steady gradients of temperature and
pressure to drive and sustain them, and these are frequently associated with
topological features such as mountain ranges or coastlines. The onshore
wind map of the United States shows this pattern, with the best wind along
a north-south corridor roughly at mid-continent (Figure 80 Meter Wind
Resource Map). Offshore winds over the Great Lakes and the east and
west coasts are stronger and steadier though they cover smaller areas. The
technical potential for onshore wind is over 8000 GW of capacity (Lu,
2009; Black & Veatch, 2007) and offshore is 800 — 3000 GW (Lu, 2009;
States used electricity in 2009 at the rate of 450 GW averaged over the day-
night and summer-winter peaks and valleys.
80 Meter Wind Resource Map Figure shows the average wind
speeds in the United States at 80 meters. Also see offshore wind
Renewable Energy Laboratory and AWS Truepower LLC
Barriers to Deployment
Renewable energy faces several barriers to its widespread deployment. Cost
is one of the most serious, illustrated in Figure Production Cost of
Electricity - 2020 Projection. Although the cost of renewables has
declined significantly in recent years, most are still higher in cost than
traditional fossil alternatives. Fossil energy technologies have a longer
experience in streamlining manufacturing, incorporating new materials,
taking advantage of economies of scale and understanding the underlying
physical and chemical phenomena of the energy conversion process. As
Figure Production Cost of Electricity - 2020 Projection shows, the lowest
cost electricity is generated by natural gas and coal, with hydro and wind
among the renewable challengers. Cost, however, is not an isolated metric;
it must be compared with the alternatives. One of the uncertainties of the
present business environment is the ultimate cost of carbon emissions. If
governments put a price on carbon emission to compensate the social cost
of global warming and the threat of climate change, the relative cost of
renewables will become more appealing even if their absolute cost does not
change. This policy uncertainty in the eventual cost of carbon-based power
generation is a major factor in the future economic appeal of renewable
energy.
2020: Production Cost of Electricity (Euros/MWh)
Natural gas: Gas Turbine
Natural gas: CCGT
Natural gas: CCGT CCS
Oil: Diesel engine
Oil: CC Oil-fired Turbine
Coal: PF
Coal: PF CCS
Coal: CFBC
Coal: IGCC
Coal: IGCC CCS
Nuclear fission
Solid biomass
Biogas
Wind: On-shore farm
Wind: Off-shore farm
Hydro: Large
Hydro: Small
Solar: CSP
Solar: Photovoltaic
® Referent COE
Production Cost of Electricity - 2020 Projection Estimates of the
cost of electricity in 2020 by fossil, nuclear and renewable generation.
Information System
A second barrier to widespread deployment of renewable energy is public
opinion. In the consumer market, sales directly sample public opinion and
the connection between deployment and public acceptance is immediate.
Renewable energy is not a choice that individual consumers make. Instead,
energy choices are made by government policy makers at city, state and
federal levels, who balance concerns for the common good, for “fairness” to
stakeholders, and for economic cost. Nevertheless, public acceptance is a
major factor in balancing these concerns: a strongly favored or disfavored
energy option will be reflected in government decisions through
representatives elected by or responding to the public. Figure Acceptance
of Different Sources of Energy shows the public acceptance of renewable
and fossil electricity options. The range of acceptance goes from strongly
positive for solar to strongly negative for nuclear. The disparity in the
public acceptance and economic cost of these two energy alternatives is
striking: solar is at once the most expensive alternative and the most
acceptable to the public.
The importance of public opinion is illustrated by the Fukushima nuclear
disaster of 2011. The earthquake and tsunami that ultimately caused
meltdown of fuel in several reactors of the Fukushima complex and release
of radiation in a populated area caused many of the public in many
countries to question the safety of reactors and of the nuclear electricity
enterprise generally. The response was rapid, with some countries
registering public consensus for drastic action such as shutting down
nuclear electricity when the licenses for the presently operating reactors
expire. Although its ultimate resolution is uncertain, the sudden and serious
impact of the Fukushima event on public opinion shows the key role that
social acceptance plays in determining our energy trajectory.
QD4 Are you in favour or opposed to the use of these different sources of energy in (OUR COUNTRY)?
BB in favour WE Balanced views IB opposed @ pk
% EU25
Solar energy | 14% || |
Wind energy | 21% | (5
Hydroelectric energy | 23% ||/9%
Ocean energy (tidal/wave/marine currents) | 24% | | 14%|
(using wood, plants La sepa | 27% _|8%/10%
Gas Pe 47% 7%)
Oil a ee
Coal Pe 49% | 20% Is
Nuclear energy a a
Source questionnaire: QD4 ” 0% 10 20 30 40 50 60 70 80 90 100%
Acceptance of Different Sources of Energy Figure shows the
European Union citizens’ public acceptance of renewable and fossil
electricity generation technologies. Source: European Commission,
Measures, p. 33
Summary
Strong interest in renewable energy arose in the 1970s as a response to the
shortage and high price of imported oil, which disrupted the orderly
operation of the economies and societies of many developed countries.
Today there are new motivations, including the realization that growing
greenhouse gas emission accelerates global warming and threatens climate
change, the growing dependence of many countries on foreign oil, and the
economic drain of foreign oil payments that slow economic growth and job
creation. There are three ultimate sources of all renewable and fossil
energies: sunlight, the heat in the earth’s core and crust, and the
gravitational pull of the moon and sun on the oceans. Renewable energies
are relatively recently developed and typically operate at lower efficiencies
than mature fossil technologies. Like early fossil technologies, however,
renewables can be expected to improve their efficiency and lower their cost
over time, promoting their economic competitiveness and widespread
deployment.
The future deployment of renewable energies depends on many factors,
including the availability of suitable land, the technological cost of
conversion to electricity or other uses, the costs of competing energy
technologies, and the future need for energy. Scenario analyses indicate that
renewable energies are likely to be technically and economically capable of
supplying the world’s electricity needs in 2050. In addition to cost, public
acceptance is a key factor in the widespread deployment of renewable
energy.
Review Questions
Exercise:
Problem:
What events in the 1970s and late 1990s motivated the modern interest
in renewable energy?
Exercise:
Problem:
Renewable energy is often divided into solar, wind, hydropower,
biomass, geothermal, wave and tide. What are the ultimate sources of
each of these renewable energies? What is the ultimate source of fossil
fuel and why is it not classified as renewable?
Exercise:
Problem:
Renewable energy has the technical potential to supply global
electricity needs in 2050. What factors determine whether renewable
energy will actually be deployed to meet this need? How can
unknowns, such as the rate of technological and economic advances,
the economic, intellectual and social connections among countries, and
the relative importance of environmental and social agendas be taken
into account in determining the course of deployment of renewable
energy?
Exercise:
Problem:
Public acceptance is a key factor in the growth of renewable energy
options. What is the public acceptance of various energy options, and
how might these change over the next few decades?
References
Attari, S.Z., DeKay, M.L., Davidson, C.I., & de Bruin, W.B. (2010). Public
perceptions of energy consumption and savings. PNAS, 107, 16054.
Black & Veatch (2007, October). Twenty percent wind energy penetration in
the United States: A technical analysis of the energy resource. Walnut
Creek, CA: Black & Veatch Corp. Retrieved December 9, 2011 from
de Vries, B.J.M., van Vuuren, D.P., & Hoogwijk, M.M. (2007). Renewable
energy sources: Their global potential for the first-half of the 21st century at
a global level: An integrated approach. Energy Policy, 35, 2590.
Jacobson, M.Z. & Delucchi, M.A. (2009). A plan for a sustainable future.
Scientific American, 301, 58.
Kaldellis, J.K. & Zafirakis, D. (2011). The wind energy (r)evolution: A
short review of a long history. Renewable Energy, 36, 1887-1901.
Lu, X., McElroy, M.B., & Kiviluoma, J. (2009). Global potential for wind-
generated electricity. PNAS, 106, 10933.
Renewables 2010 Global Status Report, REN21, Renewable Energy Policy
Network for the 21‘ Century,
http://www.ren21.net/REN21Activities/Publications/GlobalStatusReport/G
SR2010/tabid/5824/Default.aspx
Schwartz, M., Heimiller, D., Haymes, S., & Musial, W. (2010, June).
Assessment of offshore wind energy resources for the United States (NREL-
TP-500-45889). Golden, CO: National Renewable Energy Laboratory.
Retrieved December 9, 2011 from www.nrel. gov/docs/fy10o0sti/45889.pdf
Glossary
Betz’s Law
The theoretical highest possible efficiency for wind turbines, 59
percent, derived in 1919 by German physicist, Albert Betz. Click here
for more information.
economic potential
The technical potential that can be produced below a given cost
threshold, typically the cost of a specified, locally relevant alternative.
geographical potential
The energy flux for a particular renewable energy theoretically
extractable from geographical areas that are considered suitable and
available.
oil shocks
Two events of the 1970s triggered by OPEC’s oil embargo and price
increases that caused shortages of gasoline and eventually a ten fold
increase in the price oil by 1981.
scenario
A global development path based on specific assumptions for the
economic, technological and social global ccontext, predicting energy
demand, energy cost, and growth of energy technologies.
technical potential
The geographical potential after the losses due to conversion of the
primary energy flux to secondary energy carriers or forms, such as
electricity.
Fossil Fuel (Oil)
In this module, the following topics are covered: 1) the global dependence
of transportation on oil, 2) the threat to energy security posed by
concentration of oil in a few countries, 3) the challenge of capturing carbon
emissions from transportation and the value of replacing oil with an
alternate, such as biofuel or electricity.
Learning Objectives
After reading this module, the student should be able to
¢ outline the global dependence of transportation on oil
e understand the threat to energy security posed by concentration of oil
in a few countries
e understand the challenge of capturing carbon emissions from
transportation and the value of replacing oil with an alternate, such as
biofuel or electricity
Introduction
Liquid petroleum fuels and electricity are the two dominant energy.
carriers in the United States, oil accounting for 37 percent of primary
energy and electricity for 38 percent. These two energy carriers account for
a similar fraction of carbon emissions, 36 percent and 38 percent,
respectively. Two thirds of oil consumption is devoted to transportation,
providing fuel for cars, trucks, trains and airplanes. For the United States
and most developed societies, transportation is woven into the fabric of our
lives, a necessity as central to daily operations as food or shelter. The
concentration of oil reserves in a few regions or the world (Figure Crude
Oil Reserves) makes much of the world dependent on imported energy for
transportation.
The rise in the price of oil in the last decade makes dependence on imported
energy for transportation an economic as well as an energy issue. The
United States, for example, now spends upwards of $350 billion annually
on imported oil, a drain of economic resources that could be used to
stimulate growth, create jobs, build infrastructure and promote social
advances at home.
From a sustainability perspective, oil presents several challenges. First is
the length of time over which the world's finite oil reserves can continue to
supply rising demand. Second is the impact on global warming and climate
change that carbon emissions from oil combustion will have, and third is
the challenge of finding a sustainable replacement for oil for transportation.
The first challenge, how much oil is left and when its production will peak,
was discussed in Module Sustainable Energy Systems - Chapter
Introduction. The bottom line is that, as Yogi Berra famously said, making
predictions is difficult, especially about the future. Although we know the
general course of initial rise and ultimate fall that global oil production
must take, we do not know with confidence the time scale over which it will
play out.
The uncertainty of the timing of the peak in global oil production
encourages us to find other issues and motivations for dealing with an
inevitably unsustainable supply. A prime motivation is energy security, the
threat that oil supplies could be interrupted by any of several events
including weather, natural disaster, terrorism and geopolitics. Much of the
world feels these threats are good reasons for concerted effort to find
replacements for oil as our primary transportation fuel. A second motivation
is the environmental damage and accumulation of greenhouse gases in the
atmosphere due to transportation emissions. Unlike electricity generation,
transportation emissions arise from millions of tiny sources, e.g. the
tailpipes of cars and trucks and the exhaust of trains and airplanes. The
challenge of capturing and sequestering carbon dioxide from these
distributed and moving sources is dramatically greater than from the large
fixed sources of power plants. A more achievable objective may be
replacing oil as a transportation fuel with biofuel that recycles naturally
each year from tailpipes of cars to biofuel crops that do not compete with
food crops. Other options include replacing liquid fuels with electricity
produced domestically, or increasing the efficiency of vehicles by reducing
their weight, regeneratively capturing braking energy, and improving engine
efficiency. Each of these options has promise and each must overcome
challenges.
Changes in the energy system are inevitably slow, because of the time
needed to develop new technologies and the operational inertia of phasing
out the infrastructure of an existing technology to make room for a
successor. The transportation system exhibits this operational inertia,
governed by the turnover time for the fleet of vehicles, about 15 years.
Although that time scale is long compared to economic cycles, the profit
horizon of corporations and the political horizon of elected officials, it is
important to begin now to identify and develop sustainable alternatives to
oil as a transportation fuel. The timescale from innovation of new
approaches and materials to market deployment is typically 20 years or
more, well matched to the operational inertia of the transportation system.
The challenge is to initiate innovative research and development for
alternative transportation systems and sustain it continuously until the
alternatives are established.
Summary
Oil for transportation and electricity generation are the two biggest users of
primary energy and producers of carbon emissions in the United States.
Transportation is almost completely dependent on oil and internal
combustion engines for its energy. The concentration of oil in a few regions
of the world creates a transportation energy security issue. Unlike electricity
generation emissions, carbon emissions from transportation are difficult to
capture because their sources, the tailpipes of vehicles, are many and
moving. The challenges of oil energy security and capturing the carbon
emissions of vehicles motivate the search for an oil replacement, such as
biofuels, electricity or greater energy efficiency of vehicles.
Review Questions
Exercise:
Problem:
The almost exclusive dependence of the transportation system on
liquid fuels makes oil an essential commodity for the orderly operation
of many societies. What are some alternatives to oil as a transportation
fuel?
Exercise:
Problem:
There are many reasons to reduce consumption of oil, including an
ultimately finite supply, the high cost and lost economic stimulus of
payments to foreign producers, the threat of interruption of supply due
to weather, natural disaster, terrorism or geopolitical decisions, and the
threat of climate change due to greenhouse gas emissions. Which of
these reasons are the most important? Will their relative importance
change with time?
Exercise:
Problem:
The transportation system changes slowly, governed by the lifetime of
the fleet of vehicles. Compare the time required for change in the
transportation system with the timescale of economic cycles, the profit
horizon of business, the political horizon of elected officials and the
time required to develop new transportation technologies such as
electric cars or biofuels. What challenges do these time scales present
for changing the transportation system?
References
Trench, C.J. (n.d.). Oil Market Basics. U.S.Energy Information
Administration. Retrieved September 12, 2011 from
http://205.254.135.24/pub/oil_gas/petroleum/analysis publications/oil mar
ket_basics/default.htm
Glossary
energy carrier
A medium, such as electricity, gasoline or hydrogen, that can move
energy from one place to another, usually from the point of production
(e.g. an electrical generator or petroleum refinery) to the point of use
(e.g. an electric light or motor or a gasoline engine).
The Conversion of Biomass into Biofuels
In this module, the following topics are covered: 1) the social and
environmental motivations for biofuels production, 2) the main types of
catalytic and biocatalytic routes to produce biofuels and biochemicals, 3)
alcohol (ethanol and butanol) biofuels and hydrocarbon biofuels (green
gasoline, diesel, and jet fuel).
Learning Objectives
After reading this module, students should be able to
e understand the social and environmental motivations for biofuels
production
e learn the main types of catalytic and biocatalytic routes to produce
biofuels and biochemicals
e compare alcohol (ethanol and butanol) biofuels to hydrocarbon
biofuels (green gasoline, diesel, and jet fuel)
Introduction
Biofuels are fuels made from biomass. The best known example is ethanol,
which can be easily fermented from sugar cane juice, as is done in Brazil.
Ethanol can also be fermented from broken down (saccarified) corn starch,
as is mainly done in the United States. Most recently, efforts have been
devoted to making drop-in replacement hydrocarbon biofuels called green
gasoline, green diesel, or green jet fuel. This chapter discusses the need for
biofuels, the types of biofuels that can be produced from the various
available biomass feedstocks, and the advantages and disadvantages of each
fuel and feedstock. The various ways of producing biofuels are also
reviewed.
The Need for Renewable Transportation Fuels
In crude oil, coal, and natural gas, (collectively called fossil fuels) our
planet has provided us with sources of energy that have been easy to obtain
and convert into useful fuels and chemicals. That situation will soon
change, however, in a few decades for petroleum crude and in a few
centuries for coal and natural gas. Peak oil refers to the peak in oil
production that must occur as petroleum crude runs out. As shown in Figure
Peak Oil — The Growing Gap, the main discoveries of crude oil occurred
prior to 1980.
Discovery
Consumption
Billions of Barrels/Year
1930 1940 1950 1960 1970 1980 1990 2000 2010 2020 2030
ne
Projected Discoveries
Peak Oil — The Growing Gap Petroleum crude
oil discoveries versus refined oil production.
Source: Rep. Roscoe Bartlett, Maryland
Since oil is getting harder and harder to find, we now have to obtain it from
less accessible places such as far under the ocean, which has led to hard-to-
repair accidents such as the Deepwater Horizon oil spill in May, 2010. An
additional effect is the higher cost of refining the petroleum since it comes
from more remote locations or in less desirable forms such as thick, rocky
“tar sand” or “oil sand” found in Canada or Venezuela. Overall, the use of
petroleum crude cannot exceed the amount of petroleum that has been
discovered, and assuming that no major oil discoveries lie ahead, the
production of oil from crude must start to decrease. Some analysts think
that this peak has already happened.
An additional aspect of oil scarcity is energy independence. The United
States currently imports about two thirds of its petroleum, making it
dependent on the beneficence of countries that possess large amounts of oil.
These countries are shown in Figure The World According to Oil, a world
map rescaled with the area of each country proportional to its oil reserves.
Middle Eastern countries are among those with the highest oil reserves.
With its economy and standard of living so based on imported petroleum
crude it is easy to see why the United States is deeply involved in Middle
East politics. It should be noted that Figure Peak Oil — The Growing Gap
corresponds to the entire world and even currently oil-rich countries such as
Saudi Arabia will soon experience peak oil.
Who has the oil?
oo mene a ee ee
Ie ee
Ae
nt ae heme ae pom a te
— _
mn nn
a
rere ee eee ee =
Pees sseSe52e7
The World According to Oil World map redrawn with country area
proportional to oil resources. Source: Rep. Roscoe Bartlett, Maryland
A second major motivation to move away from petroleum crude is global
climate change. While the correlation of carbon dioxide (CO>)
concentration in the atmosphere to average global temperature is presently
being debated, the rise of CO, in our atmosphere that has come from
burning fossil fuel since the industrial revolution is from about 280 ppm to
about 390 ppm at present, and cannot be denied. Energy sources such as
wind, solar, nuclear, and biomass are needed that minimize or eliminate the
release of atmospheric CO». Biomass is included in this list since the carbon
that makes up plant fiber is taken from the atmosphere in the process of
photosynthesis. Burning fuel derived from biomass releases the CO, back
into the atmosphere, where it can again be incorporated into plant mass.
advanced biofuel as one that lowers lifecycle greenhouse gas emissions
(emissions from all processes involved in obtaining, refining, and finally
burning the fuel) by 60% relative to the baseline of 2005 petroleum crude.
First Generation Biofuels
First generation biofuels are commonly considered to be ethanol, as has
been produced in Brazil for over 30 years from sugar cane, and biodiesel
produced by breaking down, in a process called transesterification,
vegetable oil. Brazil can efficiently harvest the juice from its sugar cane and
make ethanol, which is price-competitive with gasoline at cost per mile.
Gas/Ethanol Fuel Pump A fuel pump in Brazil
offering either ethanol alcohol (A) or gasoline
(G). Source:_Natecull
There, if the cost of alcohol (as it is known colloquially) is less than 70%
than the cost of gasoline, tanks are filled with ethanol. If the cost of alcohol
is more than 70% of the cost of gasoline, people fill up with gasoline since
there is about a 30% penalty in gas mileage with ethanol. This comes about
simply because the chemical structure of ethanol has less energy per
volume (about 76,000 Btu/gallon or 5,100 kcal/liter) than gasoline (115
Btu/gallon or 7,600 kcal/liter) or diesel (132,000 Btu/gallon or 8,800
kcal/liter). Cane ethanol qualifies, per EISA 2007, as an advanced biofuel.
In the United States, for a cost of about twice that of cane-derived ethanol,
com starch is saccharified and fermented into ethanol. Ethanol is used
predominantly as a high octane, oxygenated blend at 10% to improve the
combustion in gasoline engines. The distribution of ethanol as E85 flex fuel
(85% ethanol and 15% gasoline) has faltered probably because the price,
even with a 50 cents/gallon federal subsidy, does not make up for the 25 —
30% decrease in gas mileage (see Figure Mileage Comparisons).
2011 Flexible Fueled Vehicles
Sorted by MPG (city), Click on column headings to resort
Select up to 4 models to compare
Estimated annual ar oo
New MPG Fuel Carbon Footprint yy ctscs except
city hwy Cost (tonstyr of CO) CA and NE states
Chevrolet Malibu 4 cyl, 2.4 L, Automatic (S6), FFV, Gasoline or E85
233 0 GE
15 23 soso
Ford Fusion FWD FFY 6 cyl, 3.0 L, Automatic (S6), FFV, Gasoline or E85
20 28 sors ED
4 21 300 EB
Chrysler Town and Country 6 cyl, 3.6 L, Automatic 6-spd, FFV, Gasoline or E85
25 $2730 P93 |
18 soar QED
Mileage Comparisons Mileage comparison of
gasoline and E85 flex fuel. Source: U.S.
Department of Energy, Energy Efficiency and
Renewable Energy. Image created at
http://www. fueleconomy.gov/feg/byfueltype.htm
First generation biodiesel is made via the base catalyzed transesterification
of plant oils such as soy and palm. The main disadvantage with plant oil-
based biofuels is the high cost of the plant oil, owing to the relatively little
oil that can be produced per acre of farmland compared to other biofuel
sources. The problem with transesterification is that it produces a fuel
relatively high in oxygen, which a) causes the biodiesel to become cloudy
(partially freeze) at relatively high temperature, and makes the biodiesel b)
less stable, and c) less energy dense than petroleum-derived diesel.
Cane ethanol qualifies as an advanced biofuel, as its production lowers
greenhouse gas emissions more than 60% relative to the 2005 petroleum
baseline (per EISA 2007). Corn ethanol is far from this energy efficiency.
However, ethanol made from lignocellulose — the non-food part of plants -
comes close, at a 50% reduction. This brings us to the second generation of
biofuels.
Second Generation Biofuels
Second generation biofuels are shown in Figure Second Generation
Biofuels. In anticipation of the “food versus fuel” debate, EISA 2007
placed a cap on the production of corn ethanol (at 15 billion gallons/year,
close to what is now produced), with the bulk of biofuels to be derived from
agricultural residues such as corn stover (the parts of the corn plant left over
from the ears of corn — the stalk and leaves) and wheat straw, forest waste
(wood trimmings) and energy crops such as switchgrass and short rotation
poplar trees which can be grown on abandoned or marginal farmland with
minimal irrigation and fertilization. A U.S. Department of Agriculture study
commissioned in 2005 called the Billion Ton Study estimated that
approximately one billion tons per year of biomass could be sustainably
produced in the United States each year; the energy in this biomass equals
to the amount of oil we import. If the energy contained in this biomass can
be recovered at an efficiency of 50 percent, we can replace half of our
imported oil with domestically produced biofuels.
lignin —» Heat/Power
Butanol
Ethanol
Jet Fuel
Diesel
Second Generation Biofuels Cellulosic ethanol and green
diesel. Source: John Regalbuto
Collectively termed “lignocellulose,” this material consists of three main
components; cellulose, hemicellulose, and lignin. Chemical or biological
pretreatments are required to separate the whole biomasss into these
fractions. Hemicellulose and cellulose, with the appropriate enzymes or
inorganic acids, can be deconstructed into simple sugars and the sugars
fermented into ethanol, or with some newer strains of microbes, into
butanol. Butanol has only 10% less energy density than gasoline. The lignin
fraction of biomass is the most resistant to deconstruction by biological or
chemical means and is often burned for heat or power recovery.
At the same time attention turned toward cellulosic ethanol, petroleum
refining companies set about to improve biodiesel. A petroleum refining
process called hydrotreating was used to upgrade plant oil. In this process,
the oil is reacted with hydrogen in the presence of inorganic catalysts, and
the plant oil is converted into a much higher quality, oxygen-free “green
diesel” and jet fuel. This type of biofuel is in fact a “drop in replacement” to
petroleum-derived diesel and jet fuel and passes all of the stringent
regulations demanded by the automobile and defense industries. It has been
tested in a number of commercial and military aircraft.
“Advanced” Biofuels
Advanced biofuels are, in fact, characterized by their similarity to present
day gasoline, diesel, and jet fuels. Advanced biofuels are infrastructure
compatible and energy_dense. The two disadvantages with even cellulosic
ethanol are its low energy density (the energy content of ethanol being
independent of whether it comes from corn, cellulose, etc.) and its
incompatibility with existing car engines, oil pipelines, storage tanks,
refineries, etc. For these two reasons the latest research and development
efforts in the United States have been devoted to hydrocarbon biofuels,
which have the same gas mileage as the gasoline and diesel fuels now used,
and are completely compatible with the existing oil infrastructure.
aAMoODCON
Forest Waste Corn Stover
oe
Thermal Routes
———_____—————
Catalytic Routes
ee
Biological Routes
oo
Synthetic Biology
or-mecn OMMHHMOOAD
Routes to Advanced Biofuels Various routes to drop-in replacement
hydrocarbon biofuels. Source: John Regalbuto
The various routes to drop-in replacement hydrocarbon biofuels are shown
in Figure Routes to Advanced Biofuels. On the left side of the figure,
feedstocks are ordered relative to their abundance and cost. The most
abundant and, therefore, cheapest feedstock is lignocellulose from sources
such as agricultural residue, forest waste, and energy crops such as switch
grass and short rotation poplar trees. Of lesser abundance and higher
expense are the sugars and starches — corn and sugar cane. The least
abundant and most expensive biofuels, lipid-based feedstocks from plant oil
or animal fat, are shown at the bottom. Efforts are underway to mass
produce oil-laden algae. The oils harvested from algae are relatively easy to
convert to hydrocarbon biofuels, by using processing similar to
hydrotreating. The main set of problems associated with algae lie in its
mass production. Algal feedstocks are easy to convert to hydrocarbons but
algae itself is difficult to mass produce, whereas lignocellulose is very
abundant but more difficult to convert into hydrocarbons.
Two of the routes to hydrocarbon biofuels compete directly with
fermentation of sugars to ethanol. The same sugars can be treated with
inorganic catalysts, via the blue liquid phase processing routes seen in the
center of Figure Routes to Advanced Biofuels, or with microbial routes to
yield hydrocarbons as the fermentation product (pink routes). Microbes are
examples of biocatalysts; enzymes within the microbe act in basically the
same way that inorganic catalysts act in inorganic solutions. The field of
research in which enzymes are engineered to alter biological reaction
pathways is called synthetic biology.
A flow sheet of an inorganic catalytic set of processes to hydrocarbon
biofuels, from a leading biofuel startup company (Virent Energy Systems of
Madison, Wisconsin) is shown in Figure Inorganic Catalytic Routes to
Advanced Biofuels. Both of the biocatalytic and the inorganic catalytic
processes involve an intrinsic separation of the hydrocarbon product from
water, which eliminates the energy intensive distillation step needed for
alcohol fuels. For the microbial route the added benefit of this self-
separation is that the microbes are not poisoned by the accumulation of
product as occurs in fermentation to alcohol.
Inorganic Catalytic Routes to Advanced Biofuels A flow sheet of
an inorganic catalytic set of processes to hydrocarbon biofuels, from
a leading biofuel startup company, Virent Energy Systems. Source:
Virent Energy Systems, figure 1
Two other main routes to hydrocarbon biofuels are seen in the upper section
of Figure Routes to Advanced Biofuels: gasification and pyrolysis. An
advantage of both of these routes is that they process whole biomass,
including the energy-rich lignin fraction of it. Gasification produces a
mixture of carbon monoxide and hydrogen called synthesis gas, which can
be converted to hydrocarbon fuels by a number of currently commercialized
catalytic routes including Fischer-Tropsch synthesis and methanol-to-
gasoline. The challenge with biomass is to make these processes
economically viable at small scale. The second process is pyrolysis, which
yields a crude-like intermediate called pyrolysis oil or bio-oil. This
intermediate must be further treated to remove oxygen; once this is done it
can be inserted into an existing petroleum refinery for further processing.
Summary
The motivations for hydrocarbon biofuels are energy independence and a
reduction in greenhouse gas emissions. The first renewable biofuels were
biodiesel and bioethanol. With inorganic catalysis and synthetic biology,
these have been supplanted with drop-in replacement gasoline, diesel, and
jet fuels. These can be made in the United States in a number of ways from
presently available, sustainably produced lignocellulosic feedstocks such as
corm stover, wood chips, and switchgrass, and in the future, from mass-
produced algae. It is too early to tell which production method will prevail,
if in fact one does. Some processes might end up being particularly
advantageous for a particular feedstock such as wood or switchgrass. What
we do know is that something has to be done; our supply of inexpensive,
easily accessible oil is running out. Biofuels will be a big part of the
country’s long-term energy independence. A great deal of scientific and
engineering research is currently underway; it’s an exciting time for
biofuels.
Review Questions
Exercise:
Problem:
What are the potential advantages of hydrocarbon biofuels over
alcohol biofuels?
Exercise:
Problem:
How could biofuels be used with other alternate energy forms to help
the United States become energy independent?
Glossary
biocatalysis
Catalysis conducted by enzymes — catalysis within the body, for
example.
energy density
The amount of energy contained in a given volume (say a gas tank).
The higher the energy density of a fuel, the farther the car will go on a
tank of the fuel.
fermentation
The conversion of sugars into alcohols or hydrocarbons by microbes.
Fischer-Tropsch synthesis
The inorganic catalytic reaction between CO and H) (synthesis gas),
which produces diesel and jet fuel.
gasification
The conversion of biomass at very high temperature (1000 — 1200°C)
in an oxygen atmosphere that results in a “synthesis gas” intermediate
—a mixture of carbon monoxide (CO) and hydrogen (H>).
hydrotreating
Reaction in the presence of hydrogen.
infrastructure compatible
Compatible with existing oil pipelines, storage tanks, petroleum
refineries, and internal combustion engines.
inorganic catalysis
Solid, inorganic materials such as platinum nanoparticles deposited
onto activated carbon, which accelerate the rate of chemical reactions
without being consumed in the process.
lignocellulose
The non-food portion of plants such as the stalks and leaves of corn
plants (corn stover).
peak oil
The peak in world oil production that must come about as oil
consumption surpasses the discovery of new oil.
pyrolysis
The conversion of biomass at moderately high temperature (500 —
800°C) in an inert atmosphere that results in a “bio-oil” intermediate.
synthetic biology
The field of biology in which microbes are engineered to control
metabolic pathways.
transesterification
The base catalyzed reaction of plant oil with methanol with breaks the
oil into long fatty acid chains, which can be used as a low quality
diesel fuel.
Geothermal Heating and Cooling
In this module, the following topics are covered: 1) the basic
thermodynamic principles of a heat, 2) geothermal heating and cooling, 3)
different types of geothermal systems and the principles that govern their
design.
Learning Objectives
After reading this module, students should be able to
e understand the basic thermodynamic principles of a heat
¢ learn what makes geothermal heating and cooling more efficient than
conventional systems
¢ compare different types of geothermal systems and the principles that
govern their design
Introduction
With limited supplies of fossil fuels in the coming decades and increasing
awareness of environmental concerns related to combustions of fossil fuels,
alternate energy sources such as geothermal are becoming increasingly
attractive. Geothermal energy is energy that comes from the earth. In this
section we describe the basic principles of geothermal energy systems and
the energy savings that can result from their use.
The Heat Pump
The key to understanding a geothermal energy system is the heat pump.
Normally heat goes from a hot area to a cold area, but a heat pump is a
device that enables heat to be transferred from a lower temperature to a
higher temperature with minimal consumption of energy (see Figure A
Simple Heat Pump). A home refrigerator is an example of a simple heat
pump. A refrigerator removes heat from the inside of a refrigerator at
approximately 3°C, 38°F (See Heat In in the Figure A Simple Heat Pump)
and then discards it to the kitchen (at approximately 27°C, 80°F (See Heat
Out in Figure A Simple Heat Pump). It is pumping heat from the inside of
the refrigerator to the outside using a compressor, hence the name heat
pump.
The fact the most fluids boil at different temperatures when pressure is
changed[footnote] is crucial to the operation of the heat pump. Boiling
removes heat from the environment, just like boiling water takes heat from
the stove. In a heat pump, boiling takes place at a lower pressure and,
consequently, at a lower temperature. Let’s assume 40°F, or 4°C, so that it
can effectively remove heat from the soil or the pond water (the heat
source) in the geothermal unit at 50°F, or 10°C. The steam produced from
the boiling can then be compressed (see Compressor in Figure A Simple
Heat Pump) to higher pressure so that it will condense (the opposite of
boiling) at a much higher temperature. When a geothermal unit is
incorporated into a building, it is the building that removes the heat,
subsequently warming it up (See Heat Out in Figure A Simple Heat
Pump). The condensed steam in a geothermal heat pump will thus provide
heat at a much higher temperature to the area being heated than the original
heat source. Finally a throttle, similar to a water faucet at home, is used to
lower the pressure (See Expansion Valve in Figure A Simple Heat Pump)
to complete the closed system cycle, which is then repeated. By switching
the direction of the heat pump, the geothermal system can be used for
cooling as well.
This is the same reason why water boils at lower temperatures at higher
elevations where pressure is lower, for example in Boulder, Colorado.
Compressor
Heat In Heat Out
L H
o 2. Compression i
w g
h
P P
r 1. Evaporation 3. Condensation r
4 e
. s
i s
u
r 4. Expansion r
e e
Expansion Valve
A Simple Heat Pump A typical vapor compression heat pump for
cooling used with a Geothermal System. Source: Sohail Murad
adapted from Ilmari Karonen
Geothermal Heating and Cooling
Geothermal systems are suited to locations with somewhat extreme
temperature ranges. Areas with moderate temperature ranges (e.g. some
areas of California) can use ordinary heat pumps with similar energy
savings by adding or removing heat to/from the outside air directly. Areas
that experience somewhat extreme temperatures (e.g. the Midwest and East
Coast) are ideal target locations for geothermal systems. For regions with
moderate climates, such as many parts of the South or the West Coast,
conventional heat pumps, that exchange energy generally with the outside
air, can still be used with similar energy savings. Geothermal heat pumps
(GHPs) use the almost constant temperatures (7°C to 8°C, or 45°F to 48°F)
of soil beneath the frost line as an energy source to provide efficient heating
and cooling all year long. The installation cost of GHPs is higher than
conventional systems due to additional drilling and excavation expenses,
but the added cost is quickly offset by GHPs’ higher efficiency. It is
possible to gain up to 50 percent savings over conventional heating and
cooling systems (see Figure Estimated Cooling Costs Comparison),
which allows the additional capital costs from installation to be recovered,
on average, in less than 5 years. GHP’s have an average lifespan of over 30
years, leaving 25 years or more of heating/cooling savings for those willing
to make the investment. In addition, GHPs are space efficient and, because
they contain fewer moving components, they also have lower maintenance
costs.
Chilled Water Single Zone Multi-Zone Rooftop
Rooftop
Estimated Cooling Costs Comparison Estimated cooling costs of
geothermal systems compared with conventional systems. Source:
Sohail Murad
Types of Geothermal Systems
There are two major types of geothermal systems: in ground and pond
systems. In ground geothermal systems can be vertical and horizontal as
shown in Figure In Ground Geothermal Systems. The excavation cost of
vertical systems is generally higher and they require more land area for
installation, which is generally not an option in urban locations. Other than
excavation costs, vertical and horizontal GHPs have similar efficiencies
since the ground temperature below the frost line is essentially constant.
Closed Loop Systems
Closed Loop Systems Vertical
Horizontal
In Ground Geothermal Systems Examples of horizontal and
vertical ground systems. Source: U.S. Department of Energy,
Energy Efficiency and Renewable Energy
Pond geothermal systems are generally preferable if there is water available
in the vicinity at almost constant temperature year round. These systems are
especially suited to industrial units (e.g. oil refineries) with water treatment
facilities to treat processed water before it is discharged. The temperature of
treated water from these facilities is essentially constant throughout the year
and is an ideal location for a pond system. Pond geothermal systems are
constructed with either open loops or closed loops (see Figure Pond
Geothermal Systems). Open loop systems actually remove water from the
pond, while the close loop systems only remove energy in the form of heat
from the pond water. Of course, in open pond system this water is again
returned to the pond, albeit at a lower temperature when used for heating.
Closed Loop Systems Open Loop Systems
Pond/Lake
Pond Geothermal Systems Examples of closed and open loop
pond systems. Source: U.S. Department of Energy, Energy
Efficiency and Renewable Energy
Economics of Geothermal Systems
As stated earlier, depending upon the type of system, the capital and
installation cost of a geothermal system is about twice the cost of a
traditional heating, ventilation, air conditioning (HVAC) system.
However, both the operating and maintenance costs are much lower and
switching from heating to cooling is effortless. A typical return of
investment (ROI) plot for a ground geothermal system for a multi-unit
building is favorable (see Figure Return of Investment in Geothermal
System). A geothermal system that had an additional $500,000 in capital
costs but lower operating and maintenance costs allowed the added cost to
be recouped in 5 to 8 years. Since the average lifespan of a geothermal
system is at least 30 years, the savings over the lifetime of the system can
be substantial. The efficiency of ground geothermal systems is fairly
constant since there are no large variations in ground temperature. The
efficiency for pond systems would, in general, be much higher than those
shown in Figure Return of Investment in Geothermal System if, during
the winter months, the pond water temperature is higher than typical ground
temperatures below the frost line (7°C - 8'C, or 44 F - 48 'F) because the
efficiency of heat pumps increases with higher heat source temperature.
Another reason for higher efficiency of pond systems is the much higher
heat transfer rate between a fluid and the outer surface of the geothermal
pipes, especially if the water is flowing.
$1,600,000
$1,200,000
$800,000
Project Investment
Project Year
Return of Investment in Geothermal System Return of additional
capital investment in a typical geothermal system. Source: Murad, S.,
& Al-Hallaj, S. from Feasibility Study For a Hybrid Fuel
Cell/Geothermal System, Final Report, HNTB Corporation, August
2009.
Increasing Efficiency of Geothermal Systems
Several strategies are available to increase the efficiency of geothermal
systems. One of the most promising possibilities is to use it in conjunction
with phase change materials (PCM) (see also Module Applications of
Phase Change Materials for Sustainable Energy), particularly to handle
peak loads of energy consumptions. Phase change materials are materials
that can absorb and deliver much larger amounts of energy compared to
typical building materials. The cost of geothermal systems unlike other
HVAC systems increases almost linearly with system size (approximately
$1000/ton). Thus, building larger systems to account for peak loads can
significantly add to both the capital and installation costs. PCM can be
incorporated into all four geothermal systems described earlier. The best
approach is to incorporate PCMs with geothermal systems for applications
in systems with non-uniform energy requirements, or systems with short but
significant swings and peaks in energy needs. For example, designers may
include snow melting heating systems for train platforms or they may build
a buffer energy reservoir using PCMs to satisfy peak needs of cooling on a
hot summer afternoon. The advantages in the former application would be
to avoid running the geothermal system for heat loads at low temperatures
over prolonged periods, which would not be as energy efficient and would
require specially designed systems.
Using phase change materials allows for the use of standard geothermal
systems, which would then store energy in a PCM unit to supply heat at a
constant temperature and at a uniform heat rate to, for example, melt the
snow on train platforms. Once the energy in the PCM is nearly used the
geothermal system would repower the PCM storage. The extra energy
needs for peak periods could be stored in PCM Storage Tanks and then used
to address such needs. For example, on a hot summer day, the PCM unit can
be used to remove additional heat above the designed capacity of the
geothermal system during temperature spikes, which generally last only a
few hours. This then reduces the load on the geothermal system during peak
hours when electricity cost is generally the highest.
PCM Storage Tanks reduce the overall cost of the geothermal heat pump
system significantly since it does not have to be designed to address peak
heating/cooling needs. In addition, it also shifts energy loads from peak
hours to non-peak hours. Figure Temperature Variation shows
temperature variations for a typical summer day in July 2010 in Chicago.
The high temperature of 90 degree lasted only for a short period of about 4
hours, and then returned to below 85 degrees rapidly. These relatively short
temperature peaks can be easily managed by PCMs.
\O
co)
oO
a)
—]
LA
Temperature ("F)
Co
Oo
I
i)
0 400 800 1200 1600 2000 2400
Time Measured During One Day
Temperature Variation Temperature variation during a typical
July day in Chicago. Source: Sohail Murad produced figure using
data from Great Lakes Environmental Research Laboratory
In conclusion, geothermal heat pumps are a very attractive, cost efficient
sustainable energy source for both heating and cooling with a minimal
carbon print. It is a well-developed technology that can be easily
incorporated into both residential and commercial buildings at either the
design stage or by retrofitting buildings.
Review Questions
Exercise:
Problem: On what principle does a geothermal heat pump work?
Exercise:
Problem:
What makes it more cost efficient than electrical heating or
conventional furnaces?
Exercise:
Problem:
Are geothermal heat pumps suitable for moderate climates (e.g.
Miami, FL)? Are conventional electrical or gas furnaces the only
choices in these areas?
Glossary
geothermal energy
Energy from the earth.
heat pump
A device that allows heat to be removed at a lower temperature and
supplied at a higher temperature, for example an air conditioner.
heat, ventilation and air conditioning systems (HVAC)
Systems such as furnaces and air conditioners that are commonly used
in homes and commercial buildings.
phase change materials
Materials that can absorb and deliver larger amount of heat than
common building materials because they can change their state (solid
or liquid).
Electric and Plug-in Hybrids
in this module, the following topics are covered: 1) the traditional
dependence of transportation on oil and the internal combustion engine, 2)
alternatives to oil as a transportation fuel: hydrogen and electricity. 2) the
dual use of oil and electricity in hybrid vehicles and their impact on energy
efficiency and carbon emissions.
Learning Objectives
After reading this module, students should be able to
¢ outline the traditional dependence of transportation on oil and the
internal combustion engine
e understand two alternatives to oil as a transportation fuel: hydrogen
and electricity
e understand the dual use of oil and electricity in hybrid vehicles and
their impact on energy efficiency and carbon emissions
Introduction
Since the early 20th Century, oil and the internal combustion engine have
dominated transportation. The fortunes of oil and vehicles have been
intertwined, with oil racing to meet the energy demands of the ever growing
power and number of personal vehicles, vehicles driving farther in response
to growing interstate highway opportunities for long distance personal
travel and freight shipping, and greater personal mobility producing living
patterns in far-flung suburbs that require oil and cars to function. In recent
and future years, the greatest transportation growth will be in developing
countries where the need and the market for transportation is growing
rapidly. China has an emerging middle class that is larger than the entire
population of the United States, a sign that developing countries will soon
direct or strongly influence the emergence of new technologies designed to
serve their needs. Beyond deploying new technologies, developing
countries have a potentially large second advantage: they need not follow
the same development path through outdated intermediate technologies
taken by the developed world. Leapfrogging directly to the most advanced
technologies avoids legacy infrastructures and long turnover times,
allowing innovation and deployment on an accelerated scale.
The internal combustion engine and the vehicles it powers have made
enormous engineering strides in the past half century, increasing efficiency,
durability, comfort and adding such now-standard features as air
conditioning, cruise control, hands-free cell phone use, and global
positioning systems. Simultaneously, the automobile industry has become
global, dramatically increasing competition, consumer choice and
marketing reach. The most recent trend in transportation is dramatic swings
in the price of oil, the lifeblood of traditional vehicles powered with internal
combustion engines.
Hydrogen as an Alternative Fuel
The traditional synergy of oil with automobiles may now be showing signs
of strain. The reliance of vehicles on one fuel whose price shows strong
fluctuations and whose future course is ultimately unsustainable presents
long-term business challenges. Motivated by these business and
sustainability concerns, the automobile industry is beginning to diversify to
other fuels. Hydrogen made its debut in the early 2000s, and showed that it
has the potential to power vehicles using fuel cells to produce on-board
electricity for electric motors (Eberle and von Helmholt, 2010, Crabtree,
Dresselhaus, & Buchanan, 2004). One advantage of hydrogen is efficiency,
up to 50 percent or greater for fuel cells, up to 90 percent or greater for
electric motors powering the car, compared with 25 percent efficiency for
an internal combustion engine. A second advantage is reduced dependence
on foreign oil — hydrogen can be produced from natural gas or from entirely
renewable resources such as solar decomposition of water. A third potential
advantage of hydrogen is environmental — the emissions from the hydrogen
car are harmless: water and a small amount of heat, though the emissions
from the hydrogen production chain may significantly offset this advantage.
The vision of hydrogen cars powered by fuel cells remains strong. It must
overcome significant challenges, however, before becoming practical, such
as storing hydrogen on board vehicles at high densities, finding inexpensive
and earth-abundant catalysts to promote the reduction of oxygen to water in
fuel cells, and producing enough hydrogen from renewable sources such as
solar driven water splitting to fuel the automobile industry (Crabtree &
Dresselhaus, 2008). The hydrogen and electric energy chains for
automobiles are illustrated in Figure Electric Transportation. Many
scientists and automobile companies are exploring hydrogen as a long-term
alternative to oil.
electric motor
renewable replaces
electricity gasoline engine
production
>
renewable
hydrogen
production
storage fuel cell
Electric Transportation Transportation is electrified by replacing
the gasoline engine with an electric motor, powered by electricity
from a battery on board the car (upper panel) or electricity from a
fuel cell and hydrogen storage system on board the car (lower panel).
For maximum effectiveness, both routes require renewable
production of electricity or hydrogen. Source: George Crabtree using
Energy, Office of Science
Electricity as an Alternative Fuel
Electric cars represent a second alternative to oil for transportation, with
many similarities to hydrogen (see Figure Electric Transportation). Electric
vehicles are run by an electric motor, as in a fuel cell car, up to four times as
efficient as a gasoline engine. The electric motor is far simpler than a
gasoline engine, having only one moving part, a shaft rotating inside a
stationary housing and surrounded by a coil of copper wire. Electricity
comes from a battery, whose storage capacity, like that of hydrogen
materials, is too small to enable long distance driving. Developing higher
energy density batteries for vehicles is a major challenge for the electric
car industry. The battery must be charged before driving, which can be done
from the grid using excess capacity available at night, or during the day
from special solar charging stations that do not add additional load to the
grid. Because charging typically takes hours, a potentially attractive
alternative is switching the battery out in a matter of minutes for a freshly
charged one at special swapping stations. A large fleet of electric cars in the
United States would require significant additional electricity, as much as
130 GW if the entire passenger and light truck fleet were converted to
electricity, or 30 percent of average United States electricity usage in 2008.
The energy usage of electric cars is about a factor of four less than for
gasoline cars, consistent with the higher efficiency of electric motors over
internal combustion engines. Although gasoline cars vary significantly in
their energy efficiency, a "typical" middle of the road value for a five-
passenger car is 80kWh/100km. A typical electric car (such as the Think Ox
from Norway, the Chevy Volt operating in its electric mode, or the Nissan
Leaf) uses ~ 20 kWh/100km. While the energy cost of electric cars at the
point of use is significantly less, one must consider the cost at the point of
production, the electricity generating plant. If the vehicle's electricity
comes from coal with a conversion efficiency of 33 percent, the primary
energy cost is 60 kWh/100km, approaching but still smaller than that of the
gasoline car. If electricity is generated by combined cycle natural gas
turbines with 60 percent efficiency, the primary energy cost is 33
kWh/100km, less than half the primary energy cost for gasoline cars. These
comparisons are presented in Table Comparisons of Energy Use.
Gasoline Battery Electric Nissan
Engine 5 Leaf, Chevy Volt
passenger (battery mode), Think
car Ox
Energy use at point 80
of use kWh/100km a
Energy use at point
of production: Coal 60 kWh/100km
at 33% efficiency
Combined Cycle
Natural Gas at 60% 33 kWh/100km
efficiency
Comparisons of Energy UseComparison of energy use for gasoline driven
and battery driven cars, for the cases of inefficient coal generation (33%)
and efficient combined cycle natural gas generation (60%) of electricity.
Source: George Crabtree.
Gasoline Battery Electric Nissan
Engine 5 Leaf, Chevy Volt
passenger (battery mode), Think
car Ox
CO2 Emissions at A1 lbs a,
point of use
CO2 Emissions at 42 lbs
point of production
Coal@2.1 lb
CO2/kWh
Gas@1.3 Ib
CO2/kWh ——
Nuclear, hydro, wind <1]b
or solar
Comparisons of Carbon EmissionsComparison of carbon emissions from
gasoline driven and battery driven cars, for the cases of high emission coal
generation (2.1 lb CO2/kWh), lower emission natural gas (1.3 IbCO2/kWh)
and very low emission nuclear, hydro, wind or solar electricity. Source:
George Crabtree.
The carbon footprint of electric cars requires a similar calculation. For coal-
fired electricity producing 2.1 lb CO,/kWh, driving 100km produces 42 lbs
(19 kgs) of carbon dioxide; for gas-fired electricity producing 1.3 lb
CO,/kWh, 100km of driving produces 26 Ibs (11.7 kgs) of carbon dioxide.
If electricity is produced by nuclear or renewable energy such as wind, solar
or hydroelectric, no carbon dioxide is produced. For a "typical" gasoline
car, 100km of driving produces 41 Ibs (18.5 kgs) of carbon dioxide. Thus
the carbon footprint of a "typical" electric car is, at worst equal, to that of a
gasoline car and, at best, zero. Table Comparisons of Carbon Emissions
summarizes the carbon footprint comparisons.
The Hybrid Solutions
Unlike electric cars, hybrid vehicles rely only on gasoline for their power.
Hybrids do, however, have a supplemental electric motor and drive system
that operates only when the gasoline engine performance is weak or needs a
boost: on starting from a stop, passing, or climbing hills. Conventional
gasoline cars have only a single engine that must propel the car under all
conditions; it must, therefore, be sized to the largest task. Under normal
driving conditions the engine is larger and less efficient than it needs to be.
The hybrid solves this dilemma by providing two drive trains, a gasoline
engine for normal driving and an electric motor for high power needs when
starting, climbing hills and passing. The engine and motor are tailored to
their respective tasks, enabling each to be designed for maximum
efficiency. As the electric motor is overall much more efficient, its use can
raise fuel economy significantly.
The battery in hybrid cars has two functions: it drives the electric motor and
also collects electrical energy from regenerative braking, converted from
kinetic energy at the wheels by small generators. Regenerative braking is
effective in start-stop driving, increasing efficiency up to 20 percent. Unlike
gasoline engines, electric motors use no energy while standing still; hybrids
therefore shut off the gasoline engine when the car comes to a stop to save
the idling energy. Gasoline engines are notoriously inefficient at low speeds
(hence the need for low gear ratios), so the electric motor accelerates the
hybrid to ~15 mph (24 kph) before the gasoline engine restarts. Shutting the
gasoline engine off while stopped increases efficiency as much as 17
percent.
The energy saving features of hybrids typically lower their energy
requirements from 80 kWh/100km to 50-60 kWh/100km, a significant
savings. It is important to note, however, that despite a supplementary
electric motor drive system, all of a hybrid's energy comes from gasoline
and none from the electricity grid.
The plug-in hybrid differs from conventional hybrids in tapping both
gasoline and the electricity grid for its energy. Most plug-in hybrids are
designed to run on electricity first and on gasoline second; the gasoline
engine kicks in only when the battery runs out. The plug-in hybrid is thus
an electric car with a supplemental gasoline engine, the opposite of the
conventional hybrid cars described above. The value of the plug-in hybrid
is that it solves the "driving range anxiety" of the consumer: there are no
worries about getting home safely from a trip that turns out to be longer
than expected. The disadvantage of the plug-in hybrid is the additional
supplemental gasoline engine technology, which adds cost and complexity
to the automobile.
The Battery Challenge
To achieve reasonable driving range, electric cars and plug-in hybrids need
large batteries, one of their greatest design challenges and a potentially
significant consumer barrier to widespread sales. Even with the largest
practical batteries, driving range on electricity is limited, perhaps to
~100km. Designing higher energy density batteries is currently a major
focus of energy research, with advances in Li-ion battery technology
expected to bring significant improvements. The second potential barrier to
public acceptance of electric vehicles is charging time, up to eight hours
from a standard household outlet. This may suit overnight charging at
home, but could be a problem for trips beyond the battery's range — with a
gasoline car the driver simply fills up in a few minutes and is on his way.
Novel infrastructure solutions such as battery swapping stations for long
trips are under consideration.
From a sustainability perspective, the comparison of gasoline, electric,
hybrid and plug-in hybrid cars is interesting. Hybrid cars take all their
energy from gasoline and represent the least difference from gasoline cars.
Their supplementary electric drive systems reduce gasoline usage by 30-40
percent, thus promoting conservation of a finite resource and reducing
reliance on foreign oil. Electric cars, however, get all of their energy from
grid electricity, a domestic energy source, completely eliminating reliance
on foreign oil and use of finite oil resources. Their sustainability value is
therefore higher than hybrids. Plug-in hybrids have the same potential as all
electric vehicles, provided their gasoline engines are used sparingly. In
terms of carbon emissions, the sustainability value of electric vehicles
depends entirely on the electricity source: neutral for coal, positive for gas
and highly positive for nuclear or renewable hydro, wind or solar. From an
energy perspective, electric cars use a factor of four less energy than
gasoline cars at the point of use, but this advantage is partially
compromised by inefficiencies at the point of electricity generation. Even
inefficient coal-fired electricity leaves an advantage for electric cars, and
efficient gas-fired combined cycle electricity leaves electric cars more than
a factor of two more energy efficient than gasoline cars.
Summary
Electricity offers an attractive alternative to oil as a transportation fuel: it is
domestically produced, uses energy more efficiently, and, depending on the
mode of electricity generation, can emit much less carbon. Electric vehicles
can be powered by fuel cells producing electricity from hydrogen, or from
batteries charged from the electricity grid. The hydrogen option presents
greater technological challenges of fuel cell cost and durability and high
capacity on-board hydrogen storage. The battery option is ready for
implementation in the nearer term but requires higher energy density
batteries for extended driving range, and a fast charging or battery swapping
alternative to long battery charging times.
Review Questions
Exercise:
Problem:
Transportation relies almost exclusively for its fuel on oil, whose price
fluctuates significantly in response to global geopolitics and whose
long-term availability is limited. What are the motivations for each of
the stakeholders, including citizens, companies and governments, to
find alternatives to oil as a transportation fuel?
Exercise:
Problem:
Electricity can replace oil as a transportation fuel in two ways: by on
board production in a hydrogen fuel cell, and by on board storage in a
battery. What research and development, infrastructure and production
challenges must be overcome for each of these electrification options
to be widely deployed?
Exercise:
Problem:
Electric- and gasoline-driven cars each use energy and emit carbon
dioxide. Which is more sustainable?
Exercise:
Problem:
How do gasoline-driven, battery-driven and hybrid cars (like the Prius)
compare for (i) energy efficiency, (ii) carbon emissions, and (iii)
reducing dependence on foreign oil?
References
Crabtree, G.W., Dresselhaus, M.S., & Buchanan, M.V. (2004). The
Hydrogen Economy, Physics Today, 57, 39-45. Retrieved September 2,
2011 from
Crabtree, G.W. & Dresselhaus, M.S. (2008). The Hydrogen Fuel
Alternative. MRS Bulletin,33, 421-428. Retrieved September 2, 2011 from
http://www. physics.ohio-state.edu/~wilkins/energy/Resources/harnessing-
mtl-energy/hfuel.pdf
Doucette, R.T. & McCulloch, M.D. (2011). Modeling the CO2 emissions
from battery electric vehicles given the power generation mixes of different
countries. Energy Policy, 39, 803-811. doi: 10.1016/j.enpol.2010.10.054
Eberle, U. & Helmolt, R.V. (2010). Sustainable transportation based on
electric vehicle concepts: a brief overview. Energy and Environmental
Science, 3, 689-699. doi: 10.1039/C001674H
Glossary
Energy Density
The energy contained in a volume or mass divided by the volume or
mass it occupies. High energy density materials pack a large energy
into a small space or mass; low energy density materials require more
space or mass to store the same amount of energy. The electrical
energy of batteries is at the low end of the energy density scale, the
chemical energy of gasoline is at the high end, approximately a factor
of 30-50 larger than batteries.
Hybrid Vehicle
A car that contains two drive systems, one based on the internal
combustion engine and one on the electric motor. Conventional
hybrids, such as the Toyota Prius, use the electric motor only when
high power is needed: starting from a stop, passing, and going uphill.
The electricity to run the motor is generated on board by an alternator
powered by the internal combustion engine and by regenerative
breaking. Plug-in hybrids such as the Chevy Volt, in contrast, use the
electric motor as the main drive for the car, relying on the gasoline
engine only when the battery is low or empty.
Internal Combustion Engine
The engine that converts the chemical energy of gasoline into the
mechanical energy of motion, by exploding small amounts of fuel in
the confined space of fixed cylinder containing a moving piston. A
precise amount of fuel must be metered in, and a spark created at a
precise moment in the piston's journey to produce the maximum
explosive force to drive the piston. The internal combustion engine is
an engineering marvel (the word engineering celebrates it) perfected
over more than a century. In contrast, the electric motor is much
simpler, more efficient and less expensive for the same power output.
Point of Production
The first (or at least an early) step in the energy chain, where the
energy that ultimately will perform a function at the point of use is put
into its working form. For gasoline-driven cars, this is the refinery
where gasoline is produced from crude oil, for battery-driven cars this
is the power generation plant were electricity is produced. Gasoline is
then delivered to the pump and finally to the car, where it is converted
(the point of use) to mechanical motion by the engine. Similarly,
electricity is delivered to the battery of an electric car by the grid, and
converted by the electric motor of the car (the point of use) to
mechanical motion.
Point of Use
The last step in the energy chain, where energy accomplishes its
intended function. For vehicles, this is the conversion of chemical
energy in gasoline cars or electric energy in battery cars to motion of
the wheels that moves the car along the road.
Combined Heat and Power
In this module, the following topics are covered: 1) combined heat and
power (CHP) as an alternative energy source, 2) CHP component
characteristics and operational benefits, 3) the characteristics of good CHP
applications.
Learning Objectives
After reading this module, students should be able to
e define combined heat and power (CHP) as an alternative energy source
e provide CHP component characteristics and operational benefits
e outline the characteristics of good CHP applications
Introduction
Electricity in the United States is generated, for the most part, from central
station power plants at a conversion efficiency of roughly 30 to 35 percent.
Meaning, for every 100 units of fuel energy into a simple cycle central
station electric power plant, we get only 30 to 35 units of electricity. The
remainder of the energy in the fuel is lost to the atmosphere in the form of
heat.
The thermal requirements of our buildings and facilities are generally
provided on-site through the use of a boiler or furnace. The efficiencies of
this equipment have improved over the years and now it is common to have
boilers and furnaces in commercial and industrial facilities with efficiencies
of 80 percent and higher. Meaning, for every 100 units of fuel energy into
the boiler/furnace, we get about 80 units of useful thermal energy.
Commercial and industrial facilities that utilize the conventional energy
system found in the United States (electricity supplied from the electric grid
and thermal energy produced on-site through the use of a boiler/furnace)
will often times experience overall fuel efficiencies of between 40 to 55
percent (actual efficiency depends on the facilities heat to power ratio).
Combined Heat and Power (CHP) is a form of distributed generation. It is
an integrated system located at or near the building/facility that generates
utility grade electricity which satisfies at least a portion of the electrical
load of the facility, and captures and recycles the waste heat from the
electric generating equipment to provide useful thermal energy to the
facility.
Conventional CHP (also referred to as topping cycle CHP) utilizes a single
dedicated fuel source to sequentially produce useful electric and thermal
typical topping cycle CHP system. A variety of fossil fuels, renewable
fuels, and waste products are utilized as input fuel to power a prime mover
that generates mechanical shaft power (exception is fuel cells). Prime
movers might include reciprocating engines, gas turbines, steam
turbines or fuel cells. The mechanical shaft power is converted into utility
grade electricity through a highly efficient generator. Since the CHP system
is located at or near the building/facility, the heat lost through the prime
mover can be recycled through a heat exchanger and provide heating,
cooling (absorption chillers), and/or dehumidification (desiccants) to
meet the thermal load of the building. These systems can reach fuel use
efficiencies of as high as 75 to 85 percent (versus the conventional energy
system at approximately 40 to 55 percent).
15. - 30 units thecal rejected i lost
100 iantits.
fuel input 20-35 unite electric
—_—_—_—+, —
Natural Gas
Propane
Digesier Gas
Landfill Gas
Steam
Others
40 — 80 unite tieeral recovered
TO % to 65% combined
efficiency is common
Key Factor: Coincidence of Electric and Thermal Loads
Conventional (Topping Cycle) CHP Diagram illustrates a
typical topping cycle of CHP systems. Source: John Cuttica
In our example of 100 units of fuel into the CHP system, only 30 to 35 units
of electricity are generated, but another 40 to 50 units of the fuels energy
can be recovered and utilized to produce thermal power. What this tells us
is that for conventional CHP systems to reach the high efficiency level,
there must be a use for the recovered thermal energy. Thus a key factor for
conventional CHP systems is the coincidence of electric and thermal loads
in the building. This is shown in Figure Importance of Waste Heat
Recovery. The “Y” axis represents the cost of generating electricity with a
CHP system utilizing a 32 percent efficient reciprocating engine. The “X”
axis represents the cost of natural gas utilized to operate the CHP system
and also the value of the natural gas being displaced if the recycled heat
from the engine can be utilized. The lines in the chart show various levels
of recoverable heat available from the engine. If no heat is recovered (no
use for the thermal energy), the cost of generating electricity with the CHP
system is $0.08/kWhr. When the full amount of heat from the engine is
recovered (full use of the thermal energy), the cost of generating electricity
with the CHP system then drops to $0.03/kWhr.
$0.15
32% Efficient Engine Generator at |
Cost of Electricity ($/kWh)
$0.00 $2.00 $4.00 $6.00 $8.00 $10.00 $12.00
Cost of Gas ($/MMBtu)
Importance of Waste Heat Recovery Graph shows the
importance of waste heat recovery in CHP systems. Source:
John Cuttica
Since the high efficiency of a CHP system is dependent on the effective use
of the recoverable heat, CHP systems are often times sized to meet the
thermal load of the application and the amount of electricity produced is the
by-product. The electricity is used to off set the electricity otherwise
purchased from the local electric utility. When the CHP system does not
produce enough electricity to satisfy the load, the utility supplies the
difference from the grid. When the CHP system (sized from the thermal
requirements) produces more electricity than the load requires, the excess
electricity can be sold to the local utility (normally at the avoided cost of
power to the utility).
There are three general modes of operation for CHP on-site generators
relative to the electric utility grid:
e Stand Alone (totally isolated from the grid)
¢ Isolated from the grid with utility back-up (when needed)
e Parallel operation with the grid
The preferred mode of operation is parallel with the grid. Both the on-site
CHP system and the utility grid power the facility simultaneously. With a
proper sizing and configuration of the CHP system, the parallel mode of
operation provides the most flexibility. Should the grid go down, the CHP
system can keep operating (e.g. during the 2003 Northeast Blackout and the
2005 Hurricane Katrina), and should the CHP system go down, the utility
grid can supply power to the load. Overall reliability of power to the load is
increased.
The basic components of a conventional (topping cycle) CHP system are:
e Prime Mover that generates mechanical shaft energy
o Reciprocating engine
o Turbines (gas, micro, steam)
o Fuel Cell (fuel cells ustilize an electrochemical process rather
than a mechanical shaft process)
¢ Generator converts the mechanical shaft energy into electrical energy
o Synchronous generator (provides most flexibility and
independence from the grid)
o Induction generator (grid goes down — the CHP system stops
operating)
o Inverter (used mainly on fuel cells — converts DC power to
utility grade AC power)
e Waste Heat Recovery is one or more heat exchangers that capture and
recycle the heat from the prime mover
e Thermal Utilization equipment converts the recycled heat into useful
heating, cooling (absorption chillers) and/or dehumidification
(deisiccant dehumidifiers)
¢ Operating Control Systems insure the CHP components function
properly together
Reducing CO2 Emissions
In 2007, McKinsey_& Company published a study on reducing United
States greenhouse gas emissions. The report analyzed the cost and potential
impact of over 250 technology options regarding contribution to reducing
CO, emissions. Two conclusions stated in the report were:
e Abatement opportunities are highly fragmented and spread across the
economy.
e Almost 40 percent of abatement could be achieved at negative
marginal costs.
Figure Cost of CO» Reduction Technologies emphasizes both of these
points. It is interesting to point out that CHP (both industrial and
commercial applications), when sized and installed appropriately, delivers
CO, reductions at a negative marginal cost. All the technologies that show a
negative marginal cost on the chart generate positive economic returns over
the technology’s life cycle. The figure also shows that in terms of cost
effectiveness of the wide range of abatement technologies, energy
efficiency measures are by far more effective than renewable, nuclear and
clean coal generating technologies. CHP technologies stand out as having
negative marginal costs and overall positive cost effectiveness comparable
to most of the energy efficiency measures.
Cost of CO, Reduction Technologies
907
30 Potential
Gigatons’
CO, Abatement Cost (Real 2005 dollars)
-120 | Source: McKinsey & Co.
Cost of CO2 Reduction Technologies Figure shows the cost of CO»
reduction technologies. Source: Oak Ridge National Laboratory
(2008), p. 13, and McKinsey & Company, “Reducing U.S. Greenhouse
Gas Emissions: How Much at What Cost?,” December, 2007
CHP Applications
Today there are more than 3,500 CHP installations in the United States,
totaling more than 85,000 MW of electric generation. That represents
approximately 9 percent of the total electric generation capacity in the
United States. The 85,000 MW of installed CHP reduces energy
consumption by 1.9 Quads (10!° Btus) annually and eliminates
approximately 248 million metric tons (MMT) of CO> annually.
CHP systems are generally more attractive for applications that have one or
more of the following characteristics:
e Good coincidence between electric and thermal loads
e Maximum cost differential between electricity cost from the local
utility and the cost of the fuel utilized in the CHP system (referred to
as spark spread)
e Long operating hours (normally more than 3,000 hours annually)
e Need for good power quality and reliability
The following are just a few of the type applications where CHP makes
sense:
e Hospitals
e Colleges and Universities
e High Schools
e Fitness Centers
e Office Buildings
e Hotels
e Data Centers
e Prisons
e Pulp and Paper Mills
e Chemical Manufacturing Plants
e Metal Fabrication Facilities
e Glass Manufacturers
e Ethanol Plants
e Food Processing Plants
e Waste Water Treatment Facilities
e Livestock Farms
CHP Benefits
CHP is not the only solution to our energy problems. In fact, CHP is not the
most cost effective solution in all applications or in all areas of the country.
There are many variables that determine the viability of CHP installations.
However, when the technical and financial requirements of the application
are met, a well designed, installed and operated CHP system provides
benefits for the facility owner (end user), the electric utility, and society in
general. The high efficiency attained by the CHP system provides the end
user with lower overall energy costs, improved electric reliability, improved
electric power quality, and improved energy security. In areas where the
electric utility distribution grid is in need of expansion and/or upgrades,
CHP systems can provide the electric utility with a means of deferring
costly modifications to the grid. Although the electricity generated on-site
by the end user displaces the electricity purchased from the local electric
utility and is seen as lost revenue by many utilities, energy efficiency and
lower utility costs are in the best interest of the utility customer and should
be considered as a reasonable customer option by forward-looking customer
oriented utilities. Finally, society in general benefits from the high
efficiencies realized by CHP systems. The high efficiencies translate to less
air pollutants (lower greenhouse gas and NOx emissions) than produced
from central station electric power plants.
Waste Heat to Power
There is a second type of CHP system, referred to as Waste Heat to Power
(Bottoming Cycle CHP). Unlike conventional CHP where a dedicated fuel
is combusted in a prime mover, Waste Heat to Power CHP systems captures
the heat otherwise wasted in an industrial or commercial process. The waste
heat, rather than the process fuel, becomes the fuel source for the waste heat
to power system. It is used to generate steam or hot water, which in turn is
utilized to drive a steam turbine or (for lower temperatures) an organic
rankine cycle heat engine. In this case, the waste heat from the
industrial/commercial process is converted to electric power. Figure Waste
Heat to Power (Bottoming Cycle) CHP provides a diagram of a Waste Heat
to Power CHP system.
Fuel Input
SS
Thermal Energy Output
" No Additional Fuel Consumed
# No Additional On-Site Emissions
= May or May Not Generate Additional Thermal Energy
Waste Heat to Power (Bottoming Cycle) CHP Diagram illustrates
a waste heat to power (bottoming cycle) CHP system. Source: John
Cuttica
Summary
Combined Heat and Power (CHP) represents a proven and effective near-
term alternative energy option that can enhance energy efficiency, ensure
environmental quality, and promote economic growth. The concept of
generating electricity on-site allows one to capture and recycle the waste
heat from the prime mover providing fuel use efficiencies as high as 75 to
85 percent. Like other forms of alternative energy, CHP should be
considered and included in any portfolio of energy options.
Review Questions
Exercise:
Problem:
What drives the system efficiency in a conventional CHP system?
Exercise:
Problem:
To ensure high system efficiency, how would you size a conventional
CHP system?
Exercise:
Problem:
What is the preferred method of operating a CHP system that provides
the most flexibility with the utility grid?
Exercise:
Problem:
Why are CHP systems considered one of the most cost-effective CO»
abatement practices?
Exercise:
Problem:
Name at least three application characteristics that make CHP an
attractive choice.
Resources
For more information on Combined Heat and Power and Waste Heat to
Power, see www.midwestcleanenergy.org
References
Oak Ridge National Laboratory. (2008). Combined Heat and Power,
Effective Energy Solutions for a Sustainable Future. Retrieved September
26, 2011 from
http://www 1.eere.energy. gov/industry/distributedenergy/pdfs/chp_ report 12
-08.pdf
Glossary
Absorption Chiller
Utilizes heat instead of mechanical energy to provide cooling. A
thermal compressor (fueled by the waste heat from the CHP system) is
used in place of an electrically powered mechanical compressor in the
refrigeration process.
Avoided Cost of Power
The marginal cost for a utility to produce one more unit of power.
Combined Heat and Power (CHP)
An integrated system, located at or near the building or facility, that
generates utility grade electricity which satisfies at least a portion of
the electrical load of the facility and captures/ recycles the waste heat
from the electric generating equipment to provide useful thermal
energy to the facility.
Conventional CHP (Topping Cycle CHP)
Utilizes a single dedicated fuel source to sequentially produce useful
electric and thermal power.
Desiccant Dehumidification
Process that removes moisture (latent load) from a building air stream
by passing the air over a desiccant wheel (normally a silica gel). The
recovered heat from a CHP system is utilized to regenerate the
desiccant by driving the moisture off the desiccant wheel to the
outside.
Fuel Cell
An exothermic electrochemical reaction that combines hydrogen and
oxygen ions through an electrolyte material to generate electricity
(DC) and heat.
Gas Turbine
An internal-combustion engine consisting essentially of an air
compressor, combustion chamber, and turbine wheel that is turned by
the expanding products of combustion.
Induction Generator
Converts the mechanical shaft power from the CHP prime mover to
utility grade Alternating Current Power. An induction generator can
only operate when connected to an external reactive power source
(normally provided by the utility grid).
Inverter
Converts Direct Current electric power into utility grade Alternating
Current electric power. Normally used with fuel cell systems.
Organic Rankine Cycle (ORC)
Uses an organic, high molecular mass fluid with a liquid-vapor phase
change or boiling point occurring at a lower temperature than the
water-steam phase change. The fluid allows rankine cycle heat
recovery from lower temperature sources where the heat is converted
into useful work, which can then be converted into electricity.
Prime Mover
The term utilized to denote the CHP system equipment that converts
input fuel into mechanical shaft power (reciprocating engine, gas
turbine, steam turbine, micro-turbine).
Reciprocating Engine
A heat engine that uses one or more reciprocating pistons to convert
pressure into mechanical rotating shaft power.
Steam Turbine
Utilizes the Rankine Cycle to extract heat from steam and transform
the heat into mechanical shaft power by expanding the steam from
high pressure to low pressure through the turbine blades.
Synchronous Generator
Converts the mechanical shaft power from the CHP prime mover to
utility grade Alternating Current Power. A synchronous generator is
self-exciting (contains its own source of reactive power) and can
operate independent of, or isolated from, the utility grid.
Waste Heat to Power (Bottoming Cycle CHP)
Captures the waste heat generated by an industrial or commercial
process, utilizing the waste heat as the free fuel source for generating
electricity.
Applications of Phase Change Materials for Sustainable Energy
In this module, the following topics will be covered: 1) the general concept
of Phase Change Materials (PCM), 2) understand the applications of PCMs
in sustainable energy, 3) recognize the uses of PCM for heating and cooling
systems, 4) recognize the uses of PCM in buildings, 5) recognize the uses of
PCM in transportation.
Learning Objectives
After reading this module, students should be able to
e learn the general concept of Phase Change Materials (PCM)
¢ understand the applications of PCMs in sustainable energy
e recognize the uses of PCM for heating and cooling systems
e recognize the uses of PCM in buildings
e recognize the uses of PCM in transportation
Introduction
The growing demand for sustainable energy from consumers and industry is
constantly changing. The highest demand of energy consumption during a
single day brings a continuous and unsolved problem: how to maintain a
consistent desired temperature in a sustainable way. Periods of extreme cold
or warm weather are the triggering factors for increasing the demand on
heating or cooling. Working hours, industry processes, building
construction, operating policies, and type and volume of energy production
facilities are some of the main reasons for peak demand crises. Better power
generation management and significant economic benefit can be achieved if
some of the peak load could be shifted to the off peak load period. This can
be achieved by thermal storage for space heating and cooling purposes.
Thermal energy can be stored as a change in the internal energy of certain
materials as sensible heat, latent heat or both. The most commonly used
method of thermal energy storage is the sensible heat method, although
phase change materials (PCM), which effectively store and release latent
heat energy, have been studied for more than 30 years. Latent heat storage
can be more efficient than sensible heat storage because it requires a smaller
temperature difference between the storage and releasing functions. Phase
change materials are an important and underused option for developing new
energy storage devices, which are as important as developing new sources
of renewable energy. The use of phase change material in developing and
constructing sustainable energy systems is crucial to the efficiency of these
systems because of PCM’s ability to harness heat and cooling energies in an
effective and sustainable way.
Phase Change Materials for Energy Storage Devices
Thermal storage based on sensible heat works on the temperature rise on
absorbing energy or heat, as shown in the solid and liquid phases in Figure
Temperature Profile of a PCM. When the stored heat is released, the
temperature falls, providing two points of different temperature that define
the storage and release functions. Phase change materials are conceptually
different, however. They operate by storing energy at a constant
temperature while phase change occurs, for example from solid to a liquid,
as illustrated in the center of Figure Temperature Profile of a PCM. As
heat is added to the material, the temperature does not rise; instead heat
drives the change to a higher energy phase. The liquid, for example, has
kinetic energy of the motion of atoms that is not present in the solid, so its
energy is higher. The higher energy of the liquid compared to the solid is
the latent heat. When the solid is fully transformed to liquid, added energy
reverts to going into sensible heat and raising the temperature of the liquid.
Tem perature
The region
where the phase changes
ice —» woter
ice ¢~ water
time
Temperature Profile of a PCM. Figure shows the temperature
profile of a PCM. In the region where latent heat is effective, the
temperature keeps either constant or in a narrow range. The phase of
the material turns from one to another and both phases appears in the
medium. Source: Said Al-Hallaj & Riza Kizilel
A PCM is a substance with a high latent heat (also called the heat of fusion
if the phase change is from solid to liquid) which is capable of storing and
releasing large amounts of energy at a certain temperature. A PCM stores
heat in the form of latent heat of fusion which is about 100 times more than
the sensible heat. For example, latent heat of fusion of water is about
334kJ/kg whereas sensible heat at 25° Celsius (77°F) is about 4.18kJ/kg.
PCM will then release thermal energy at a freezing point during
solidification process (Figure Phase Change of a PCM). Two widely used
PCMs by many of us are water and wax. Think how water requires
significant amount of energy when it changes from solid phase to liquid
phase at 0°C (32°F) or how wax extends the burning time of a candle.
Moreover, the cycle of the melting and solidification can be repeated many
times.
PCM @
Solid Phase
Energy wae dl
% Energy In
V
Freezing Melting
@ Toonctant @ Tonctant
n
~
Energy Release \ / Energy In
PCM @
Liquid Phase
Phase Change of a PCM. Figure represents the phase change of a
PCM when the heat is applied or removed. Source: Said Al-Hallaj &
Riza Kizilel
There are large numbers of PCMs that melt and solidify at a wide range of
temperatures, making them attractive in a number of applications in the
development of the energy storage systems. Materials that have been
studied during the last 40 years include hydrated salts, paraffin waxes,
fatty acids and eutectics of organic and non-organic compounds (Figure
Energy Storage Systems). Therefore, the selection of a PCM with a
suitable phase transition temperature should be part of the design of a
thermal storage system. It should be good at heat transfer and have high
latent heat of transition. The melting temperature should lie in the range of
the operation, be chemically stable, low in cost, non-corrosive and
nontoxic.
Na,HPO,-12H,0
hydrated salts Th=40°C
Latent Heat= 279 ki/kg
Paraffin with 20 carbons
paraffin waxes Th=36.7°C
Latent Heat= 246kI/kg
ENERGY STORAGE
SYSTEMS
Stearicacid
fatty acids Th=69.4°C
Latent Heat= 199kI/kg
eutectics of organic Quinone
and non-organic Tb=115°C
compounds Latent Heat= 171 ki/kg
Energy Storage Systems. Figure shows materials commonly studied
for use in PCMs due to their ability to melt and solidify at a wide
range of temperatures. Source: Said Al-Hallaj & Riza Kizilel
Even though the list of the PCMs is quite long, only a limited number of the
chemicals are possible candidates for energy applications due to the various
limitations of the processes. Paraffins and hydrated salts are the two most
promising PCMs. Generally, paraffins have lower fusion energy than salt
hydrates but do not have the reversibility issue, i.e paraffin is only in
physical changes and keeps its composition when heat is released or gained
whereas hydrated salt is in chemical change when heat is released or
gained. Therefore, a major problem with salt hydrates is incongruent
melting, which reduces the reversibility of the phase change process. This
also results in a reduction of the heat storage capacity of the salt hydrate.
On the other hand, paraffins also have a major drawback compared to salt
hydrates. The low thermal conductivity creates a major drawback which
decreases the rates of heat stored and released during the melting and
crystallization processes and hence results in limited applications. The
thermal conductivity of paraffin used as PCM is slightly above 0.20 W/mK
(compare with ice; k;,~=~2 W/mK). Several methods such as finned tubes
with different configurations and metal matrices filled with PCM have
been investigated to enhance the heat transfer rate of PCM. Novel
composite materials of PCM, which have superior properties, have also
been proposed for various applications. For example, when PCM is
embedded inside a graphite matrix, the heat conductivity can be
considerably increased without much reduction in energy storage.
Applications of PCMs
The three applications of PCMs listed below (solar energy, buildings, and
vehicles) are only a small portion of the many areas where they can be used
(catering, telecom shelters, electronics, etc.). The applications of PCMs in
these areas have been widely studied in order to minimize the greenhouse
effect and to minimize the need for foreign gasoline which costs U.S.
economy millions of dollars every year.
Increasing concerns of the impact of fossil fuels on the environment and
their increasing cost has led to studies on thermal energy storage for the
space heating and cooling of buildings. Extreme cold or warm weather
increases the demand on heating or cooling. If the thermal energy of heat or
coolness is stored and then provided during the day or night, part of the
peak loads can be shifted to off-peak hours. Therefore, an effective energy
management and economic benefit can be achieved.
Solar energy is recognized as one of the most promising alternative energy
resource options. However, it is intermittent by nature: there is no sun at
night. The reliability of solar energy can be increased by storing it when in
excess of the load and using the stored energy whenever needed.
The minimization of heat loss or gain through walls, ceilings, and floors has
been studied for a long time and PCM applications have been considered
for more than 30 years to minimize these losses/gains, and thus reduce the
cost of electricity or natural gas use in buildings. Studies on viability of
PCMs in vehicle applications are also growing widely. Denaturation of
food during transport brings a major problem which is being partially
solved by refrigerated trucks. However, this causes not only more expensive
foods, but also irreversible environmental effects on living organisms.
Solar Energy Applications
Solar thermal energy is a technology for harnessing solar energy for thermal
energy. The solar energy is absorbed by the earth and is dissipated
throughout the ground at different rates that is dependent on the
compositions of the ground and amount of water. Ground temperature is
stable and solar energy can be transferred between the ground and space
heating/cooling places. Water heaters that use solar energy play an
important role for this purpose and they started to become popular in the
late 1960s (Figure Solar Heater). In order to utilize the energy from the sun
at all times, this precious energy should be stored and used when needed.
Passive systems using PCMs have been good candidates for thermal energy
storage and have been applied since 1980s. At first, the water heaters were
supported by filling the bottom of the heaters with PCMs, which was a first
step in storing energy in heating systems. However, the quantity of the
available energy in the storage system was limited by low thermal
conductivity of the PCM. Improvements on thermal storage systems and
developments in the incorporation of PCMs that utilize the solar energy
have been extensively studied since then.
A
Vaat
« -
>> *
filled 1 Direction of Water Flow
Solar Heater. Figure shows solar heating system with and without
PCM. Source: Said Al-Hallaj & Riza Kizilel
Later studies have mainly concentrated on increasing thermal conductivity
using composite materials. Adding PCM modules at the top of the water
tank gives the system a higher storage density and compensate for heat loss
in the top layer because of the latent heat of PCM. The configuration of the
PCM storage unit can result in advantageous control of the water
temperature rise and drop during both day and night time. Therefore,
thermally stratified water tanks are widely used for short term thermal
energy storage. Application of these tanks significantly increases not only
the energy density with the number of PCM modules, but also the cooling
period and keeps the water temperature higher compared to the ones
without PCMs. Besides, solar water heating systems operate within a wide
range of temperatures from ambient temperatures to 80°C (176°F). A
PCM has much larger heat storage capacity relative to water over a narrow
temperature range, close to its melting temperature.
A major component of total household energy consumption is cooking.
Solar energy offers an economical option for cooking in households,
especially in third world countries. A solar cooker is a device which uses
the energy of sunlight to heat food or drink to cook or sterilize it (Figure
Solar Cooker). It uses no fuel, costs nothing to operate, and reduces air
pollution. A solar cooker’s reflective surface concentrates the light into a
small cooking area and turns the light into heat. It is important to trap the
heat in the cooker because heat may be easily lost by convection and
radiation. The feasibility of using a phase change material as the storage
medium in solar cookers have been examined since 1995. A box-type solar
cooker with stearic acid based PCM has been designed and fabricated by
Buddhi and Sahoo (1997), showing that it is possible to cook food even in
the evening with a solar cooker. The rate of heat transfer from the PCM to
the cooking pot during the discharging mode of the PCM is quite slow and
more time is required for cooking food in the evening. Fins that are welded
at the inner wall of the PCM container were used to enhance the rate of heat
transfer between the PCM and the inner wall of the PCM container. Since
the PCM surrounds the cooking vessel, the rate of heat transfer between the
PCM and the food is higher and the cooking time is shorter. It is remarkable
that if food is loaded into the solar cooker before 3:30 p.m. during the
winter season, it could be cooked. However, the melting temperature of the
PCM should be selected carefully. The more the input solar radiation, the
larger quantity of heat there is ina PCM. Few examples for PCMs for solar
cooker applications are acetamide (melting point of 82 °C), acetanilide
(melting point of 118 °C), erythritol (melting point of 118 °C) and
magnesium nitrate hexahydrate (melting point of 89-90 °C).
Solar Cooker. Photograph shows solar heating
system. Source: Atlascuisinesolaire via Wikimedia
Commons.
Building Applications
PCMs can be used for temperature regulation, heat or cold storage with
high storage density, and thermal comfort in buildings that require a narrow
Therefore, if the solar energy is stored effectively, it can be utilized for
night cold. The use of PCMs brings an opportunity to meet the demand for
heating. It helps to store the energy which is available during daytime and
to keep the temperature of the building in the comfort level.
Suto SS
Typical Application of PCM in
Buildings Figure illustrates a typical
application of PCM in buildings. Heat
storage and delivery occur over a fairly
narrow temperature range. Wallboards
containing PCM have a large heat transfer
area that supports large heat transfer
between the wall and the space. Source:
Said Al-Hallaj & Riza Kizilel
Energy storage in the walls or other components of the building may be
enhanced by encapsulating PCM within the surfaces of the building. The
latent heat capacity of the PCM is used to capture solar energy or man-
made heat or cold directly and decrease the temperature swings in the
building. It also maintains the temperature closer to the desired temperature
throughout the day. Researchers have proposed macro or micro level
encapsulated PCM in concrete, gypsum wallboard, ceiling and floor in
order to achieve a reasonably constant temperature range.
Today, it is possible to improve the thermal comfort and reduce the energy
consumption of buildings without substantial increase in the weight of the
construction materials by the application of micro and macro encapsulated
PCM. The maximum and minimum peak temperatures can be reduced by
the use of small quantities of PCM, either mixed with the construction
material or attached as a thin layer to the walls and roofs of a building. In
addition, the energy consumption can also be reduced by absorbing part of
the incident solar energy and delaying/reducing the external heat load.
The absorption of heat gains and the release of heat at night by a paraffin
wax-based PCMs encapsulated within a co-polymer and sandwiched
between two metal sheets (PCM board) have been used in some building
materials. The PCM boards on a wall reduce the interior wall surface
temperature during the charging process, whereas the PCM wall surface
temperature is higher than the other walls during the heat releasing process.
The heat flux density of a PCM wall in the melting zone is almost twice as
large as that of an ordinary wall. Also, the heat-insulation performance of a
PCM wall is better than that of an ordinary wall during the charging
process, while during the heat discharging process, the PCM wall releases
more heat energy.
Unlike structural insulated panels, which exhibit fairly uniform thermal
characteristics, a PCM’s attributes vary depending upon environmental
factors. The structural insulated panel works at all times, resisting thermal
flow from hot temperatures to colder temperatures. The thermal flux is
directly proportional to the temperature difference across the structural
insulated panel insulation. The usefulness of PCM is seen when the in-wall
temperatures are such that it causes the PCM to change state. It can be
inferred that the greater the temperature difference between day and night,
the better the PCM works to reduce heat flux. The use of a phase change
material structural insulated panel wall would be excellent for geographic
areas where there is typically a large temperature swing, warm during the
day and cool at night.
Vehicle Applications
Studies on viability of PCM in vehicle applications are growing widely. For
example, PCMs are studied with regard to refrigerated trucks, which are
designed to carry perishable freight at specific temperatures. Refrigerated
trucks are regulated by small refrigeration units that are placed outside the
vehicle in order to keep the inside of the truck trailer at a constant
temperature and relative humidity. They operate by burning gas, hence the
cost of shipment is highly affected by the changes of temperature in the
trailer. The use of PCM has helped in lowering peak heat transfer rates and
total heat flows into a refrigerated trailer. Ahmed, Meade, and Medina
(2010) modified the conventional method of insulation of the refrigerated
truck trailer by using paraffin-based PCMs in the standard trailer walls as a
heat transfer reduction technology. An average reduction in peak heat
transfer rate of 29.1 percent was observed when all walls (south, east, north,
west, and top) were considered, whereas the peak heat transfer rate was
reduced in the range of 11.3 - 43.8 percent for individual walls. Overall
average daily heat flow reductions into the refrigerated compartment of
16.3 percent were observed. These results could potentially translate into
energy savings, pollution abatement from diesel-buming refrigeration units,
refrigeration equipment size reduction, and extended equipment operational
life.
Vehicles are mainly powered by gasoline (i.e gas or petrol). Liquified
petroleum gases and diesel are other types of fluids used in vehicles.
Lately, hybrid vehicles became popular among consumers as they
significantly reduce the toxic exhaust gases if the vehicles run in electric
mode. Li-ion batteries have been used in electronic devices for a long time
(cell-phones, laptops, and portable devices). Many scientists, especially in
the United States, have been working on the possibility of using Li-ion
batteries for transportation applications in order to double the fuel
efficiency and reduce emissions of hybrid vehicles. Li-ion battery modules
can be connected in order to meet the nominal voltage of the vehicle to run
the vehicle in the electric mode. However this brings a huge problem which
keeps away the uses of Li-ion batteries in many applications: as a result of
exothermic electrochemical reactions, Li-ion batteries release energy during
discharge. The generated energy should be transferred from the body of the
battery to environment. If the rate of the transfer is not sufficient, some of
the gelled phase materials turn into gas phase and increase the internal
pressure of the cell. Therefore the energy should be released from the cell as
soon as possible or the temperature of the cell should not lead to an
ion batteries with thermal management using PCM eliminate the need for
additional cooling systems and improve available power (Figure
Application with PCM Technology). The researchers maintained battery
packs at an optimum temperature with proper thermal management and the
PCM was capable of removing large quantities of heat due to its high latent
heat of fusion.
Composite PCM Li-ion Battery Battery Pack
Application with PCM Technology. A pack of Li-ion batteries kept
at a narrow temperature range with a proper use of passive thermal
management system. Source: AllCell’s PCM Technology©
Summary
There is a great interest in saving energy and in the use of renewable
energies. PCMs provide an underused option for developing new energy
storage devices in order to minimize greenhouse effects. They operate at
constant temperature; as heat is added to the material, the temperature
remains stable, but the heat drives the change to a higher energy phase. A
PCM stores heat in the form of latent heat of fusion which is about 100
times more than the sensible heat. Hydrated salts, paraffin waxes, fatty
acids and eutectics of organic and non-organic compounds are the major
types of PCMs that melt at a wide range of temperatures. The specific
melting point of the PCM determines the design of thermal storage system.
In this module, applications of PCM in solar energy, buildings, and vehicles
were reviewed. Solar heaters have been popular since 1960s and PCMs
have been used to store the precious energy from sun since 1980s. They
have been used extensively in solar cookers, especially in the third world
countries in order to decrease the thermal related costs. The cookers do not
use fuel and hence reduce air pollution.
PCM can be used for temperature regulation in order to minimize the heat
loss or gain through building walls. They have been used to capture solar
heat and decrease the temperature fluctuations in buildings. Moreover, since
a small amount of PCM is sufficient in order to store solar energy, thermal
comfort is achieved without substantial increase in the weight of the
construction materials.
Application of PCMs in transportation is growing widely. Today,
refrigerated trucks are regulated by refrigeration units, but the use of PCMs
is a viable option to prevent the denaturation of food during transportation.
The transfer rate of heat can be reduced significantly with PCMs. Moreover,
PCM makes Li-ion batteries, which have high energy density, viable for
high-power applications. The generated energy during discharge or drive
mode can be transferred from the body of the battery to environment with
the help of PCMs. Battery packs can be maintained at an optimum
temperature with proper thermal management and the PCM has been shown
to be capable of removing large quantities of heat due to its high latent heat
of fusion.
Even though there is a lot of on-going research on effective and efficient
applications of PCMs in a variety of areas (e.g. solar cookers, buildings,
vehicles), PCMs have yet to become a widely used technology for
sustainable energy. The advantages of PCMs are hardly known by many
people and, therefore, the applications of PCMs and their benefits should be
offered to consumers. The sun is out there, continuously transferring its
energy for free, but we need to do more to harness that sustainable energy
for our own needs.
Review Questions
Exercise:
Problem: Explain briefly how phase change materials work.
Exercise:
Problem:
What is the main disadvantage of the paraffin wax as a phase change
material?
Exercise:
Problem:
Name three different areas in the sustainable energy field in which
PCMs are a key element in balancing heating and cooling.
References
Ahmed, M., Meade, O., & Medina, M. A. (2010, March). Reducing heat
transfer across the insulated walls of refrigerated truck trailers by the
application of phase change materials. Energy Conversion and
Management, 51, 383-392. doi: 10.1016/j.enconman.2009.09.003
Buddhi, D. & Sahoo, L. K. (1997, March). Solar cooker with latent heat
storage: Design and experimental testing. Energy Conversion and
Management, 38, 493-498. doi: 10.1016/S0196-8904(96)00066-0
Sveum, P., Kizilel, R., Khader, M., & Al-Hallaj, S. (2007, September). IIT
Plug-in Conversion Project with the City of Chicago. Paper presented at the
Vehicle Power and Propulsion Conference, Arlington, TX. doi:
10.1109/V PPC.2007.4544174
Glossary
ambient temperature
The temperature of the surrounding environment.
denaturation
A process in which proteins or nucleic acids lose their tertiary structure
and secondary structure by application of heat.
diesel
Any liquid fuel used in diesel engines.
eutectics
A combination of two or more compounds of either organic, inorganic
or both which may have a different melting point to their individual
and separate compounds.
finned Tube
Tube with an extending part on a surface to facilitate cooling.
gas phase
One of the three classical states of matter.
gasoline
A toxic translucent, petroleum-derived liquid that is primarily used as
a fuel in internal combustion engines. The term "gasoline" is often
shortened in colloquial usage to gas. Under normal ambient conditions
its material state is liquid, unlike liquefied petroleum gas or "natural
gas."
graphite matrix
Composite material with graphite being a metal (see metal matrices).
heat of fusion
The amount of heat required to convert a unit mass of a solid at its
melting point into a liquid without an increase in temperature.
hydrated salt
A solid compound containing water molecules combined in a definite
ratio as an integral part of a crystal.
latent heat
The heat which flows to or from a material without a change to
temperature.
Li-ion battery
A type of rechargeable battery in which lithium ions move from the
negative electrode to the positive electrode during discharge and from
the positive electrode to negative electrode during charge.
liquified petroleum gas
A flammable mixture of hydrocarbon gases used as a fuel in heating
appliances and vehicles.
metal matrices
Composite material with at least two constituent parts, one being a
metal.
nominal voltage
Voltage of a fully charged cell or battery when delivering maximum
amount of energy that can be withdrawn from a battery at a specific
discharge rate.
phase change material
A material that stores heat in the form of latent heat of fusion.
paraffin
A white, odorless, tasteless, waxy solid to store heat with a specific
heat capacity of 2.14-2.9 J 9 | K ! anda heat of fusion of 200-300 J
gl
sensible heat
The heat energy stored in a substance as a result of an increase in its
temperature.
solar energy
The sun’s radiation that reaches the earth.
Problem-Solving, Metrics, and Tools for Sustainability - Chapter
Introduction
This chapter is devoted to a special collection of methods, measurements,
tools, indicators, and indices that are used to illustrate the meaning of
sustainability, to assess the comparative sustainability among options,
designs, or decisions, and to measure progress toward achieving the goals
of sustainability over time.
Introduction
“What gets measured gets done” is an oft-quoted saying (attributed to many
individuals) that attempts to capture the essential role of quantification in
order to understand a system, solve a problem, advance a cause, or establish
a policy. Throughout this text a wide variety of measurements are put forth,
cited, and discussed in connection with particular concepts including
climate change, economics, social well-being, engineering efficiency, and
consumer habits. This chapter is devoted to a special collection of methods,
measurements, tools, indicators, and indices that are used to assess the
comparative sustainability among potential and often competing options,
designs, or decisions, and to measure progress toward achieving the goals
of sustainability over time.
The chapter begins in the Module Life Cycle Assessment with a brief
discussion of industrial ecology, an emerging science that focuses on
understanding material and energy flows to and through different kinds of
human-created systems. This kind of understanding is essential for framing
problems that need to be solved in a holistic way. Industrial ecologists study
such topics as recycling and reuse of materials, energy efficiency,
organizational structures, supply chains, the social impacts of decisions, and
the economics of product development. It has been termed “the science of
sustainability” (Graedel, 2000).
One of the principal tools of industrial ecology which is discussed in this
chapter is life cycle assessment (LCA), a comprehensive set of procedures
for quantifying the impacts associated with the energy and resources needed
to make and deliver a product or service. LCA’s are carried out for two
main reasons: (a) to analyze all the steps in a product chain and see which
use the greatest amount of energy and materials or produce the most waste,
and (b) to enable comparisons among alternative products or supply chains
and to see which one create the least environmental impact. Inherent in the
concept of LCA is the notion of tradeoffs — the recognition that in a finite
world choosing one product, pathway, or way of living has consequences
for environmental and social well-being. Of course choices must be made,
but the goal of quantifying the implications of our actions as holistically as
possible is to avoid consequences that are “unintended.”
Although life cycle assessment grew out of the needs of industry to better
design products and understand the implications of their decisions, the
systemic manner of framing problems upon which LCA is based has
permeated a wide variety of fields, stimulating what might be termed “life
cycle thinking” in each of them. The Subcollection Derivative Life Cycle
Concepts in this chapter contains modules devoted to presentations of a
number of ways of expressing the impacts of humans on the environment.
These are derived from life cycle principles and are drawn from the fields
of ecology, thermodynamics, and environmental science. They include
“footprinting” and several sustainability indicators, all of which quantify
human impacts in terms of resource consumption and waste production
over an extended geographic range and/or over timeframes that go beyond
the immediate. A case study on the UN Millennium Development Goals
Indicator presents a comprehensive approach for assessing not only
environmental sustainability, but also hunger and poverty, education, gender
equity, infant mortality, maternal health, disease, and global partnerships —
all elements of sustainable development made clear in the Brundtland
report. Finally, this chapter concludes with a module about sustainability
and business.
References
Graedel, T.E. (2000). The Evolution of Industrial Ecology. Environmental
Science and Technology, 34, 28A-31A. doi: 10.1021/es003039c
Life Cycle Assessment
In this module, the following topics are covered: 1) problem solving ina
systematic and holistic manner, 2) the basic elements of life cycle analysis,
and 3) the available tools for conducting life cycle analysis.
Learning Objectives
After reading this module, students should be able to
e learn to view problem solving in a systematic and holistic manner
e understand the basic elements of industrial ecology and life cycle
analysis
e become aware of available tools for conducting life cycle analysis
Problem Solving for Sustainability
It should be clear by now that making decisions and solving problems in
support of greater sustainability of human-created systems and their impact
on the natural environment is a complex undertaking. Often in modern life
our decisions and designs are driven by a single goal or objective (e.g.
greater monetary profitability, use of less energy, design for shorter travel
times, generation of less waste, or reduction of risk), but in most cases
solving problems sustainably requires a more holistic approach in which the
functioning of many parts of the system must be assessed simultaneously,
and multiple objectives must be integrated when possible. Furthermore, as
noted in the Brundtland Report (or see Chapter Introduction to
Sustainability; Humanity and the Environment), often our decisions
require the recognition of tradeoffs — there are many kinds of impacts on the
environment and most decisions that we make create more than one impact
at the same time. Of course choices must be made, but it is better if they are
made with fuller knowledge of the array of impacts that will occur. The
history of environmental degradation is littered with decisions and solutions
that resulted in unintended consequences.
An illustrative example of the role of sustainability in solving problems is
the issue of biofuels — turning plant matter into usable energy (mostly liquid
hydrocarbon-based fuels). When viewed from afar and with a single goal,
“energy independence,” using our considerable agricultural resources to
turn solar energy, via photosynthesis, into usable fuels so that we can reduce
our dependence on imported petroleum appears to be quite attractive. The
United States is the largest producer of grain and forest products in the
world. It has pioneered new technologies to maintain and even increase
agricultural productivity, and it has vast processing capabilities to create
artificial fertilizer and to convert biomass into agricultural products (see
Module Renewable Energy: Solar, Wind, Hydro and Biomass). And,
after all, such a venture is both “domestic” and “natural” — attributes that
incline many, initially at least, to be favorably disposed. However upon
closer examination this direction is not quite as unequivocally positive as
we might have thought. Yes it is possible to convert grain into ethanol and
plant oils into diesel fuel, but the great majority of these resources have
historically been used to feed Americans and the animals that they consume
(and not just Americans; the United States is the world’s largest exporter of
agricultural products). As demand has increased, the prices for many
agricultural products have risen, meaning that some fraction of the world’s
poor can no longer afford as much food. More marginal lands (which are
better used for other crops, grazing, or other uses) have been brought under
cultivation for fermentable grains, and there have been parallel “indirect”
consequences globally — as the world price of agricultural commodities has
risen, other countries have begun diverting land from existing uses to crops
as well. Furthermore, agricultural runoff from artificial fertilizers has
contributed to over 400 regional episodes of hypoxia in estuaries around
the world, including the U.S. Gulf Coast and Chesapeake Bay.
In response to such problems, U.S. Congress passed the Energy
Independence and Security Act in 2007, which limits the amount of grain
that can be converted into biofuels in favor of using agriculturally-derived
cellulose, the chief constituent of the cell walls of plants. This has given rise
to a large scientific and technological research and development program to
devise economical ways to process cellulosic materials into ethanol, and
parallel efforts to investigate new cellulosic cropping systems that include,
for example, native grasses. Thus, the seemingly simple decision to grow
our biofuels industry in response to a political objective has had unintended
political, financial, dietary, social, land use, environmental quality, and
technological consequences.
With hindsight, the multiple impacts of biofuels have become clear, and
there is always the hope that we can learn from examples like this. But we
might also ask if there is a way to foresee all or at least some of these
impacts in advance, and adjust our designs, processes, and policies to take
them into account and make more informed decisions, not just for biofuels
but also for complex societal problems of a similar nature. This approach is
the realm of the field of industrial ecology, and the basis for the tool of life
cycle assessment (LCA), a methodology that has been designed to perform
holistic analyses of complex systems.
Industrial Ecology
Many systems designed by humans focus on maximizing profitability for
the firm, business or corporation. In most cases this means increasing
production to meet demand for the products or services being delivered. An
unfortunate byproduct of this is the creation of large amounts of waste,
many of which have significant impacts if they enter the environment.
Figure Human-Designed Industry is a general-purpose diagram of a
typical manufacturing process, showing the inputs of materials and energy,
the manufacturing of products, and the generation of wastes (the contents of
the “manufacturing box” are generic and not meant to depict any particular
industry—it could be a mine, a factory, a power plant, a city, or even a
university). What many find surprising is the large disparity between the
amounts of waste produced and the quantity of product delivered. Table
Waste-to-Product Ratios for Selected Industries provides such
information, in the form of waste-to-product ratios, for a few common
industries.
Input materials, Output wastes to
energy, & labor air, land & water
Product or service
delivered to society
Human-Designed Industry Generic representation of a human-
designed industry.Source: Theis, T.
That industrial systems designed to maximize production and/or profits
while ignoring wastes should be so materially inefficient is not surprising.
As noted in the Module Sustainability and Public Policy, the impacts of
wastes on human health and the environment have historically been
ignored, or steeply underpriced, so that little incentive has existed to limit
waste production. More recently laws have been enacted that attempt to
force those responsible for waste emissions into a more appropriate
accounting (see Chapters Environmental and Resource Economics and
Modern Environmental Management for a fuller treatment of the laws,
regulations, and practices used to incorporate society’s costs into the
production chain). Once realistic costs are assigned to the waste sector,
manufacturers are quick to innovate and investigate ways to eliminate them.
Industrial Sector Waste-to-Product Ratio
2/1 (up to 10/1 if consumer use
Automobiles is included)
Paper 10/1
Basic Metals (e.g. Steel and 30-50/1
Aluminum)
Chemicals 0.1-100/1
Nanostructured materials (e.g. 700-1700/1
computer chips)
Modern Agriculture Set
Waste-to-Product Ratios for Selected Industries: Table shows the waste
to product ratios for six common industries. Source: Theis, T.
In 1989, Robert Frosch & Nicholas Gallopoulos, who worked in the
General Motors Research Laboratory, published an important analysis of
this problem in Scientific American (Frosch and Gallopoulos, 1989). Their
paper was entitled “Strategies for Manufacturing”; in it they posed a critical
question: Why is it that human-designed manufacturing systems are so
wasteful, but systems in nature produce little, if any, waste? Although there
had been many studies on ways to minimize or prevent wastes, this was the
first to seek a systemic understanding of what was fundamentally different
about human systems in distinction to natural systems. The paper is widely
credited with spawning the new field of Industrial Ecology, an applied
science that studies material and energy flows through industrial systems.
Industrial Ecology is concerned with such things as closing material loops
(recycling and reuse), process and energy efficiency, organizational
behavior, system costs, and social impacts of goods and services. A
principle tool of Industrial Ecology is life cycle assessment.
Life Cycle Assessment Basics
LCA is a systems methodology for compiling and evaluating information
on materials and energy as they flow through a product or service
manufacturing chain. It grew out of the needs of industry, in the early
1960s, to understand manufacturing systems, supply chains, and market
behavior, and make choices among competing designs, processes, and
products. It was also applied to the evaluation of the generation and
emission of wastes from manufacturing activities. During the 1970s and
1980s general interest in LCA for environmental evaluation declined as the
nation focused on the control of toxic substances and remediation of
hazardous waste sites (see Chapters The Evolution of Environmental
Policy in the United States and Modern Environmental Management),
but increasing concern about global impacts, particularly those associated
with greenhouse gas emissions, saw renewed interest in the development of
the LCA methodology and more widespread applications.
LCA is a good way to understand the totality of the environmental impacts
and benefits of a product or service. The method enables researchers and
practitioners to see where along the product chain material and energy are
most intensively consumed and waste produced. It allows for comparisons
with conventional products that may be displaced in commerce by new
products, and helps to identify economic and environmental tradeoffs.
LCA can facilitate communication of risks and benefits to stakeholders and
consumers (e.g. the “carbon footprint” of individual activities and life
styles). Perhaps most importantly of all, LCA can help to prevent
unintended consequences, such as creating solutions to problems that result
in the transferal of environmental burdens from one area to another, or from
one type of impact to another.
A complete LCA assessment defines a system as consisting of four general
stages of the product or service chain, each of which can be further broken
down into substages:
e Acquisition of materials (through resource extraction or recycled
sources)
e Manufacturing, refining, and fabrication
e Use by consumers
e End-of-life disposition (incineration, landfilling, composting,
recycling/reuse)
Each of these involves the transport of materials within or between stages,
and transportation has its own set of impacts.
In most cases, the impacts contributed from each stage of the LCA are
uneven, i.e. one or two of the stages may dominate the assessment. For
example, in the manufacture of aluminum products it is acquisition of
materials (mining), purification of the ore, and chemical reduction of the
aluminum into metal that create environmental impacts. Subsequent usage
of aluminum products by consumers contributes very few impacts, although
the facilitation of recycling of aluminum is an important step in avoiding
the consumption of primary materials and energy. In contrast, for internal
combustion-powered automobiles, usage by consumers creates 70-80% of
the life cycle impacts. Thus, it is not always necessary that the LCA include
all stages of analysis; in many cases it is only a portion of the
product/service chain that is of interest, and often there is not enough
information to include all stages anyway. For this reason there are certain
characteristic terminologies for various “scopes” of LCAs that have
emerged:
¢ Cradle-to-grave: includes the entire material/energy cycle of the
product/material, but excludes recycling/reuse.
¢ Cradle-to-cradle: includes the entire material cycle, including
recycling/reuse.
¢ Cradle-to-gate: includes material acquisition,
manufacturing/refining/fabrication (factory gate), but excludes product
uses and end-of-life.
¢ Gate-to-gate: a partial LCA looking at a single added process or
material in the product chain.
¢ Well-to-wheel: a special type of LCA involving the application of fuel
cycles to transportation vehicles.
e Embodied energy: A cradle-to-gate analysis of the life cycle energy of
a product, inclusive of the latent energy in the materials, the energy
used during material acquisition, and the energy used in manufacturing
intermediate and final products. Embodied energy is sometimes
referred to as “emergy”, or the cumulative energy demand (CED) of a
product or service.
LCA Methodology
Over time the methodology for conducting Life Cycle Analyses (LCAs) has
been refined and standardized; it is generally described as taking place in
four steps: scoping, inventory, impact assessment, and interpretation. The
first three of these are consecutive, while the interpretation step is an
ongoing process that takes place throughout the methodology. Figure
General Framework for Life Cycle Assessment illustrates these in a
general way.
Goal and Scope
Definition
Inventory
Analysis <+——»_ Interpretation
Impact
Assessment ~~
General Framework for Life
Cycle Assessment The four
steps of life cycle assessment
and their relationship to one
another. Source: Mr3641 via
Wikipedia
Scoping
Scoping is arguably the most important step for conducting an LCA. It is
here that the rationale for carrying out the assessment is made explicit,
where the boundaries of the system are defined, where the data quantity,
quality, and sources are specified, and where any assumptions that underlie
the LCA are stated. This is critically important both for the quality of the
resultant analysis, and for comparison among LCAs for competing or
alternative products.
Inventory Analysis
The inventory analysis step involves the collection of information on the
use of energy and various materials used to make a product or service at
each part of the manufacturing process. If it is true that scoping is the most
important step in an LCA then the inventory is probably the most tedious
since it involves locating, acquiring, and evaluating the quality of data and
specifying the sources of uncertainties that may have arisen. For products
that have been produced for a long time and for which manufacturing
processes are well known, such as making steel, concrete, paper, most
plastics, and many machines, data are readily available. But for newer
products that are either under development or under patent protection, data
are often considered proprietary and are generally not shared in open
sources. Uncertainty can arise because of missing or poorly documented
data, errors in measurement, or natural variations caused by external factors
(e.g., weather patterns can cause considerable variation in the outputs of
agricultural systems or the ways that consumers use products and services
can cause variability in the emission of pollutants and the disposition of the
product at end of life). Often the manufacturing chain of a process involves
many steps resulting in a detailed inventory analysis. Figure Detailed
System Flow Diagram for Bar Soap, for example, shows the
manufacturing flow for a bar of soap (this diagram is for making bar soap
using saponification—the hydrolysis of triglycerides using animal fats and
lye). The inventory requires material and energy inputs and outputs for each
of these steps, although it may turn out that some steps contribute little to
the ultimate impact analysis. For example, the inventory associated with
capital equipment for a manufacturing process, i.e. machines that are
replaced at lengthy intervals such that their impacts in the short term are
minimal, are often omitted from the analysis.
There are two additional aspects of LCA that should also be addressed
during inventory analysis: the functional unit of comparison, and the
allocation of inventory quantities among co-products or services. The
functional unit is the basis for comparing two or more products, processes,
or services that assure equality of the function delivered. This may seem
like a straightforward task. For example, for the soap produced by the
process of Figure Detailed System Flow Diagram for Bar Soap, one
might choose “one bar of soap” as a functional unit of comparison. But then
how would a LCA comparison be made with, say, liquid hand soap or a
body wash product (which combines the functionality of soap and
shampoo)? Perhaps “number of washings” would be a better choice, or
maybe concentration of surfactant made available per average use (in the
latter case an “average dose” would need to be defined). Furthermore, soaps
have other additives and attributes such as scents, lotions, colors, and even
the functionality of the shape — factors that may not affect cleaning
effectiveness but certainly do have an impact on consumer preferences, and
hence quantity sold. Since it is quite likely that essentially all soaps
purchased by consumers will eventually be washed down the drain, such
marketability factors may indeed have an environmental impact.
Inventory data are virtually always sought for a total supply-manufacturing-
consumer-use chain rather than individual products, thus when that same
chain produces multiple products it is necessary to allocate the materials,
energy, and wastes among them. Again, referring to Figure Detailed
System Flow Diagram for Bar Soap, there are potentially several co-
products produced: tallow and other animal products, forest products,
cardboard and paper, and salable scrap. There are generally three ways to
allocate materials and energy among co-products: mass, volume, and
economic value. Mass and volume allocations are the most straightforward,
but may not capture market forces that are important in bringing materials
into the environment. Allocation via economic valuation usually reflects the
value of the energy and any “value added” to the raw materials, but may
miss the impacts of the materials themselves. In addition, market values
may fluctuate over time. In the final analysis the important aspect of any
allocation procedure is that it be fully documented.
Detailed System Flow Diagram for Bar Soap The
manufacturing flow for a bar of soap (this diagram is for
making bar soap using saponification—the hydrolysis of
triglycerides using animal fats and lye). Source: (U.S.
Environmental Protection Agency, 2006)
Impact Assessment
material resources used, energy consumed, and wastes emitted by the
system and estimates potential impacts on the environment. At first glance,
given that an inventory may include thousands of substances, it may seem
that the number of potential impacts is bewilderingly large, but the problem
is made more tractable through the application of a system of impact
classifications within which various inventory quantities can be grouped as
having similar consequences on human health or the environment.
Sometimes inventoried quantities in a common impact category originate in
different parts of the life cycle and often possess very different
chemical/biological/physical characteristics. The LCIA groups emissions
based on their common impacts rather than on their chemical or physical
properties, choosing a reference material for which health impacts are well
known, as a basic unit of comparison. A key aspect is the conversion of
impacts of various substances into the reference unit. This is done using
characterization factors, some of which are well-known, such as global
warming potential and ozone depletion potential, and LC-9 (the
concentration of a substance at which fifty percent of an exposed population
is killed), and others are still under development. Table Common Impact
Categories and Their References presents several impact categories that
are frequently used in the LCIA along with their references. The categories
listed in Table Common Impact Categories and Their References are not
exhaustive — new types of impact categories, such as land use and social
impacts — and continue to be developed.
Human Health (cancer) Kg Benzene eq/unit
Human Health (non-cancer) LCs eq from exposure modeling
Global Climate Change Kg CO, eq/unit
Eutrophication Kg Nitrogen eq/unit
EcotoxicityAquatic, Kg 2,4 D eq/unitLCs 9 eq from
Terrestrial Toxicity exposure modeling
Acidification Kg H*/unit
Smog Formation Kg Ethane eq/unit
Stratospheric Ozone ;
Depletion Kg CFC-11 eq/unit
Common Impact Categories and Their References: Several impact
categories that are frequently used in the LCIA along with their references.
Source: T. Theis adapted from (U.S. Environmental Protection Agency,
2006)
An example will help to illustrate the type of information that results from
life cycle inventory _and impact assessments. In this case, a system that
produces a biologically-derived plastic, polylactide, is examined. (PLA).
PLA has been proposed as a more sustainable alternative to plastics
produced from petroleum because it is made from plant materials, in this
case corn, yet has properties that are similar to plastics made from
schematic of the system, which is a cradle-to-gate assessment. As with any
plastic, PLA can be turned into a variety of final products and each will
have different cradle-to-grave LCA characteristics. The production of PLA
involves growing corn, harvesting and processing the grain, and
polymerizing the lactic acid molecules produced from fermentation. At
each step a variety of chemicals and energy are used or produced. It is these
production materials that contribute to the impact analysis. Inventory
quantities were allocated among major bio-products on a mass basis.
System Boundaries
Fertilizers ___»
& chemicals
” farm/ag chemicals emissions
energy/ fay
"SS * Corn Steep Liquor
oA — > emissions from Fossil
| Fuel combustion energy/
Tr biosolids rd chemicals
nutrients, ma
chemicals
treatment
FF waste heat/water
emissions
Processing Diagram for Making Polylactide (PLA) The production
of PLA involves growing corn, harvesting and processing the grain,
and polymerizing the lactic acid molecules produced from
fermentation. At each step a variety of chemicals and energy are used
or produced. It is these production materials that contribute to the
impact analysis. Source: Landis, A.E. (2007)
Among the inventory data acquired in this case is life cycle fossil fuel used
by the system, mostly to power farming equipment (“Agriculture”), wet-
mill corn (“CWM7”), heat fermentation vats (“Ferment”), and
Polymerization (“Polym”). The transport of intermediate products from
sources to the processing center is also included. Figure Fossil Fuel Use to
Make PLA vs. Petroleum-Based Plastics shows the fossil fuel used to
make PLA compared with fossil fuel used for making several petroleum-
based plastics. Figure Global Warming Potential Impact Analysis shows
the global warming potential impact analysis. As might have been expected,
the fossil fuels used to make PLA are slightly less than for the petroleum-
derived plastics on an
MJ/kg polymer
Fossil Fuel Use
Fossil Fuel Use to Make PLA vs. Petroleum-Based Plastics The
amount of fossil fuels used when making PLA is slightly less in
comparison to making several petroleum-based products. (note: PS-
GPPS — General Purpose Polystyrene; HDPE — High Density
Polyethylene; PET — Polyethylene Terephthalate; LDPE — Low
Density Polyethylene; PP — Polypropylene). Source: Landis, A.E.
using data from: PLA-L, PLA-L2, (Landis, A.E., 2007); PLA-V, (Vink,
et al., 2003); PLA-B, (Bohlmann, 2004); PLA-P, (Patel, et al.,_2006).
kg CO2-eq/kg polymer
o}- N WwW hekum ete N
PLA-L PLA-L2 PLAV PLA-B PS-GPPS HDPE PET LDPE PP
Global Warming Potential Impact Analysis Global
warming impact for PLA compared with several
other petroleum- derived plastics. Source: Landis,
A.E. (2007)
equal mass basis (the functional unit is one kilogram of plastic). The PLA
inventory also shows the sources of fossil fuel used for each step along the
manufacturing chain, with the fermentation step being the most intense
user. What may not be obvious is that the total greenhouse gases (GHG)
emitted from the process, on an equivalent carbon dioxide (CO>) basis, are
generally higher for the biopolymer in comparison with the petroleum
polymers in spite of the lower fossil fuel usage. When the data are
examined closely this is due to the agricultural step, which consumes
generates relatively little fossil fuel, but is responsible for a disproportionate
amount of emissions of GHGs, mostly in the form of nitrous oxide, a
powerful greenhouse gas (310 times the global warming potential of CO2)
that is a by-product of fertilizer application to fields. This example also
illustrates counter-intuitive results that LCAs often generate, a principal
reason why it is important to conduct them.
Interpretation of LCA
The interpretation step of LCA occurs throughout the analysis. As noted
above, issues related to the rationale for conducting the LCA, defining the
system and setting its boundaries, identifying data needs, sources, and
quality, and choosing functional units, allocation procedures, and
appropriate impact categories must all be addressed as the LCA unfolds.
There are essentially two formal reasons for conducting an LCA: (a)
identification of “hot spots” where material and/or energy use and waste
emissions, both quantity and type, are greatest so that efforts can be focused
on improving the product chain; and (b) comparison of results between and
among other LCAs in order to gain insight into the preferable product,
service, process, or pathway. In both cases, there are cautions that apply to
the interpretation of results.
Assumptions
Typically a variety of assumption must be made in order to carry out the
LCA. Sometimes these are minor, for example, exclusion of elements of the
study that clearly have no appreciable impact on the results, and sometimes
more critical, for example choosing one set of system boundaries over
another. These must be explicitly stated, and final results should be
interpreted in light of assumptions made
Data Quality, Uncertainty, and Sensitivity
In the course of conducting an LCA it is usually the case that a variety of
data sources will be used. In some cases these may be from the full-scale
operation of a process, in others the source is from a small scale or even
laboratory scale, in still other cases it may be necessary to simulate
information from literature sources. Such heterogeneity inevitably leads to
uncertainty in the final results; there are several statistical methods that can
be applied to take these into account. An important aspect of the completed
LCA is the degree of sensitivity the results display when key variables are
perturbed. Highly sensitive steps in the chain have a greater need to narrow
uncertainties before drawing conclusions with confidence.
Incommensurability
Sometimes LCA impact categories, such as those shown in Table Common
Impact Categories and Their References, overlap in the sense that the
same pollutant may contribute to more than one category. For instance, if a
given assessment comes up with high scores for both aquatic toxicity and
human toxicity from, say, pesticide use then one might be justified in using
both of these categories to draw conclusions and make choices based on
LCA results. However, more typically elevated scores are found for
categories that are not directly comparable. For instance, the extraction,
refining, and use of petroleum generate a high score for global warming
(due to GHG release), while the product chain for the biofuel ethanol has a
high score for eutrophication (due to nitrogen release during the farming
stage). Which problem is worse — climate change or coastal hypoxia?
Society may well choose a course of action that favors one direction over
another, but in this case the main value of the LCA is to identify the
tradeoffs and inform us of the consequences, not tell us which course is
“correct.”
Risk Evaluation and Regulation
One of the inherent limits to LCA is its use for assessing risk. Risk
assessment and management, as described in the Modules The Evolution
of Environmental Policy in the United States and Modern
Environmental Management, is a formal process that quantifies risks for a
known population in a specific location exposed to a specific chemical for a
defined period of time. It generates risk values in terms of the probability of
a known consequence due to a sequence of events that are directly
comparable, and upon which decisions on water, land, and air quality
standards and their violation can be and are made. LCA is a method for
evaluating the impacts of wastes on human health and the environment
from the point of view of the product/service chain rather than a particular
population. It can be used to identify the sources of contamination and
general impacts on the environment — a sort of “where to look” guide for
regulation, but its direct use in the environmental regulatory process has
been, to date, rather limited. One application for LCA that has been
suggested for regulatory use is for assessing the impacts of biofuel
mandates on land use practices, in the United States and other regions,
however no regulatory standards for land use have yet been proposed.
Tools for Conducting LCA
Fortunately a number of databases and tools, in the form of computer
software, are available to assist in carrying out LCAs. This is an active area
of development; in this section a few of the more well-known and widely
used tools are described.
The Greenhouse Gases, Regulated Emissions, and Energy Use in
Transportation Model (GREET)
GREET is a spreadsheet-based database developed by Argonne National
Laboratory that links energy use to emissions on a life cycle basis. Early
versions were limited to greenhouse gases, but as the model has been
refined many other types of contaminants have been added. Although it has
been widely used for comparing transportation and fuel options (hence its
title), GREET has been used for many other applications that have a
significant energy component, including agriculture, material and product
development, and strategies for recycling.
SimaPro
SimaPro was developed by PRé Consultants in the Netherlands. It is a
process-based tool for analyzing products and systems for their energy
usage and environmental impacts over their life cycle. It contains a number
of databases for simulating processes, performing inventories, assembling
products and systems, analyzing results, and assessing life cycle impacts,
and features modules for performing uncertainty and sensitivity analyses.
Tool for the Reduction and Assessment of Chemical and Other
Environmental Impacts (TRACI)
TRACT is a tool for performing life cycle impact analyses developed by the
U.S. Environmental Protection Agency. It uses inventory data as input
information to perform a “mid-point” impact analysis using categories such
as those shown in Table Common Impact Categories and Their
References. A mid-point analysis assesses impact based upon results at a
common point in the risk chain, for example, global warming potential,
because subsequent end-point impact assessments require several
assumptions and value choices that often differ from case to case. The
values for the various impact categories given in Table Common Impact
Categories and Their References are mid-point references.
Economic Input Output Life Cycle Assessment (EIO-LCA)
EIO-LCA (http://www.eiolca.net/) takes a different approach to the
development of a life cycle assessment. In comparison with the somewhat
complicated “bottom-up” approach described above, EIO-LCA uses a more
aggregated, matrix-based approach in which the economy is composed of
several hundred “sectors,” each linked to the other through a series of
factors. EIO was first developed in the 1950s by Wassily Leontief (1905-
1999) who was awarded a Nobel Prize in economics for his work. EIO has
proven to be a very useful tool for national and regional economic planning.
The developers of EIO-LCA then linked the main economic model to a
series of environmental impacts. EIO-LCA uses economic measures to
perturb the system; for example, if a factory seeks to increase its output by
ten percent, then the aggregated inputs across the economy will have to
increase by ten percent. Of course some of the inputs from some sectors
will increase very little if at all, while others will bear the major brunt of the
increase in output by increasing input. In EIO-LCA, part of the new outputs
will be increased contaminant loads to the environment.
EIO-LCA has several advantages in comparison with the “bottom-up”
approach. There is no need to be concemed with defining system
boundaries, i.e. the “boundary” is the entire economy of the United States
(or a sub-region), which includes all material and energy inputs and outputs.
The data used in EIO-LCA are, for the most part, already collected by the
federal government thereby obviating the tedium of the inventory stage.
Finally, software models are readily available to carry out the analysis.
While a “bottom-up” LCA may take months or even years to complete,
EIO-LCA typically takes a few hours.
Of course, at this level of aggregation much information is lost, especially
on how the system actually functions. For example, the “energy” sector of
the economy includes electricity generated, but doesn’t distinguish among
nuclear, fossil, or renewable sources. And if one is concerned with the
functional reasons for a particular result, EIO-LCA will be of limited use.
Often the “bottom-up” and EIO-LCA approaches are combined (a “hybrid”
approach).
Conclusions
The life cycle approach is a useful way to come to an understanding of the
material and energy needed to make a product or deliver a service, see
where wastes are generated, and estimate the subsequent impacts that these
wastes may have on the environment. It is a good way to improve a product
chain, articulate tradeoffs, and make comparisons among alternative
processes and products. In these contexts LCA facilitates decision making
by managers, designers, and other stakeholders. Most importantly, LCA is a
way of framing policy options in a comprehensive and systematic way.
Review Questions
Exercise:
Problem:
Using the information in Table Waste-to-Product Ratios for Selected
Industries, fill in numerical values, per unit of product, for the
diagram in Figure Human-Designed Industry. One diagram for each
industrial sector.
Exercise:
Problem:
What are some of the reasons to use Life Cycle Assessments?
Exercise:
Problem:
What are the basic stages of a product or service chain that serve as the
basis for a life cycle assessment?
Exercise:
Problem:
What are the steps involved in performing a life cycle assessment?
Exercise:
Problem:
Name several characteristic scopes of life cycle assessments.
Exercise:
Problem: What is “embodied energy”?
Exercise:
Problem:
Name several impact assessment categories and the reference units
typically used to express them.
Exercise:
Problem:
Name several life cycle impact analysis tools and their major
characteristics.
Exercise:
Problem: What are some of the limitations of life cycle assessments?
Exercise:
Problem:
Locate and read a completed Life Cycle Assessment online. Consider
whether widespread adoption by society would result in measureable
lowering of environmental impacts? If so what kind? What might the
obstacles be? Are there any tradeoffs associated with adoption, i.e.
some impacts may be reduced, but others might get worse?)
References
Bohlmann, G. M. (2004). Biodegradable packaging life cycle assessment.
Environmental Progress, 23(4), 49-78. doi: 10.1002/ep.10053
Frosch, R. & Gallopoulos, N. (1989). Strategies for Manufacturing.
Scientific American, 261(3), 144-152.
Landis, A. E. (2007). Environmental and Economic Impacts of Biobased
Production. Unpublished doctoral dissertation, University of Illinois at
Chicago.
Patel, M., Crank, M., Dornburg, V., Hermann, B., Roes, L., Huesling, B., et
al. (2006, September). Medium and long term opportunities and risks of the
biotechnological production of bulk chemicals from renewable resources —
The potential of white biotechnology: The BREW Project. Utrecht
University, Netherlands: European Commission’s GROWTH Programme
(DG Research).
U.S. Environmental Protection Agency. (2006). Life cycle assessment:
Principles and practice. (EPA Publication No. EPA/600/R-06/060).
Systems Analysis Branch, National Risk Management Research Laboratory.
Vink, E. T. H., Rabagno, K.R., Glassner, D.A., & Gruber, P.R. (2003).
Applications of life cycle assessment to NatureWorks polylactide (PLA)
production. Polymer Degradation and Stability 80(3), 403-419. doi:
10.1016/S0141-3910(02)00372-5
Glossary
allocation
For a chain which produces multiple products or services, the
partitioning of inventory quantities among these co-products or co-
services.
economic input output life cycle assessment (EIO-LCA)
An aggregated approach to LCA in which the environmental impacts
of a product or service are determined through an analysis of the
complete economy.
functional unit
The basis for comparing two or more products, processes, or services
that assures equality of the function delivered.
industrial ecology
An applied science that is concerned with material and energy flows
through industrial systems.
life cycle assessment (LCA)
A method for quantifying the materials and energy needed to make or
deliver a product or service that assesses the wastes produced and
potential environmental impacts across all or a part of the product
chain.
life cycle impact assessment (LCIA)
The stage of an LCA in which the environmental impacts associated
with the manufacture and delivery use and disposal of a product are
calculated.
life cycle inventory (LCI)
The stage of an LCA in which information on the use of energy and
various materials used to make a product or service at each part of the
manufacturing process is collected.
scoping
The stage of a LCA in which the rationale for carrying out the
assessment is made explicit, where the boundaries of the system are
defined, where the data quantity, quality, and sources are specified, and
where any assumptions that underlie the LCA are stated.
Sustainability Metrics and Rating Systems
In this module, the following topics are covered: 1) the challenges are when
measuring sustainability, 2) commonly used measures for sustainability, 3)
the different types of measures and their value within a measuring system.
Learning Objectives
After reading this section, students should be able to
e understand what the challenges are when measuring sustainability
¢ be able to compare and contrast some commonly used measures for
sustainability
e identify the different types of measures and their value within a
measuring system
Introduction
The ideal method to measure sustainability would reflect the three-legged
stool paradigm — environmental protection, social equity, and economic
benefit. The metrics must make the connection between what the indicators
measure and actual sustainability. A useful indicator will reflect changes
over time that show whether a system is becoming more or less sustainable,
and generally substitutes for something else or represents several measures
(Sahely, 2005). The challenge of studying sustainability as an objective
science is that the work is value-loaded and socially charged. If we are
aware of the purpose of the analysis we can use a multidisciplinary
approach to the problem definition and the research methodology (Lele and
Norgaard, 1996).
Rules of data collection
Information Pyramid The
Information Pyramid shows
ways of handling data when
studying sustainability.
Source: CG. Klein-Banai.
In general, three approaches to sustainability measurement and reporting
are commonly utilized: accounts that use quantitative data and convert
them to a common unit such as money, area or energy; Narrative
assessments that include text, maps, graphics and tabular data; and
indicator-based systems that may include the information that a narrative
assessment has but they are organized around indicators or measurable parts
of a system. Indicator-based systems are generally found to perform better
and are easily measurable and comparable since they are more objective
than narrative systems, or use only individual data points (Dalal-Clayton,
2002). Decision-makers and stakeholders need to participate in the
development of indicators to be sure that their values and concerns are
addressed. However, the system does need to be technically and
scientifically based.
In the next few modules we will briefly discuss existing sustainability
metrics that are generally based within certain disciplines such as ecology,
economics, and physics, and how they may reflect other disciplines (see
Table Common Sustainability Metrics). Most of these metrics are
described in greater details in the following modules: The IPAT Equation,
Biodiversity, Species Loss, and Ecosystem Function, ‘Tragedy _of the
and Life Cycle Assessment.
Method Brief Description Use
Economic Captures the
Contingent preferences of the
valuation public regarding a Good or
method good or service by service
(CVM) measuring its
willingness to pay
Valuation of
services provided
Ecosystem
of by nature such as Good or
services ,
cleaning of water service
valuation by
microorganisms
Method
Cost
Benefit
Analysis
(CBA)
Index of
Sustainable
Economic
Welfare
(ISEW)
Net
national
product
(NNP)
Green
NNP
Brief Description
Valuation of cost
and benefits for
each year of
project/policy;
calculation of a net
present value
(NPV) by
aggregating and
comparing costs
and benefits over
the whole life of
project policy.
Weights personal
expenditures with
an index of
income inequality
Total income of
the people in an
economy less
capital
consumption or
depreciation
Modification of
above to account
for loss of natural
resource Capital
Use
Project or
policy
Regional
welfare
Regional
welfare
Regional
welfare
Ecological
Physical
Method
Resilience
Carrying
capacity:
Maximum
sustainable
yield
(MSY) &
IPAT
Ecological
footprint
(EF)
Emergy
Brief Description
Intensity of
disturbance
required to move
system to anew
regime
The maximum
amount of
resource extraction
while not
depleting the
resource from one
harvest to the next
Total area of
productive land
and water
ecosystems needed
to produce
resources and
assimilate waste of
a given population
The amount of
solar energy that
has been used
directly or
indirectly to make
a good or service
Use
Ecosystem
Ecosystem
Individual,
institutional,
regional
Good or
service
Method Brief Description Use
The maximum
work that can be
extracted from a Policy,
Exergy system when it evaluation
moves towards of energy
thermodynamic systems
equilibrium with a
reference state
Common Sustainability MetricsTable lists common sustainability metrics.
Source: C. Klein-Banai
Ecological Measures
Ecological measures of sustainability are used for natural systems. These
measures include resilience and several constructs that are derivatives from
carrying capacity. Resilience is the time needed for a system that provides
desirable ecosystem goods and services to go back to a defined dynamic
regime after disturbance. Resilience stresses the changing nature of
ecosystems, rather than seeing them as static and providing a continuous
society’s total use of the resource stocks and flows provided by an
ecosystem relative to the remaining resources needed by the ecosystem for
stability and regeneration. Maximum sustainable yield (MSY) is an
outgrowth of carrying capacity and the goal is to reach the maximum
amount of resource extraction while not depleting the resource from one
harvest to the next. Sustainability, in this context, can be understood as the
point when the rate of resource extraction or harvest (MSY) equals the
amount produced by the ecosystem. Previously discussed methods are types
of measures of sustainability such as IPAT (see Module ‘The IPAT
Equation) which accounts for the effect of society on the amount of
resources used when looking at carrying capacity. This type of measure
looks at whether the impact of a human society is increasing or decreasing
over time and can be used to compare impacts between societies of
difference sizes or affluence levels.
Footprinting (see Module Footprinting: Carbon, Ecological and Water)
is often used as a measure of sustainability that can be understood
intuitively and is, therefore, useful when talking to the general public. The
ecological footprint, which also represents the carrying capacity of the
earth, is defined as “the total area of productive land and water ecosystems
required to produce the resources that the population consumes and
assimilate the wastes that the population produces, wherever on Earth that
land and water may be located” (Rees and Wackernagel, 1996). This results
in an evaluation of the demand and supply of natural capital of a given
population (individual to planet) or a product/service.
Life-cycle assessment (LCA), a structured methodology that can be utilized
to evaluate the environmental impacts of products, processes, projects, or
services throughout their life cycles from cradle to grave (see Module Life
Cycle Assessment) may be considered an ecological metric. A greenhouse
gas emissions inventory is an example of this methodology (see Case
Study: Greenhouse Gases and Climate Change).
Economic Measures
Economic measures place a monetary value on sustainability. Economists
use the following measures of sustainability: ecosystem valuation,
contingent valuation, and net national product, which are discussed in
Chapter Environmental and Resource Economics. Standard economic
methods can be used to evaluate environmental projects.
Indices that are used on a national and international level by organizations
like the United Nations may be used to examine the economic and social
welfare of a region. The Index of Sustainable Economic Welfare (ISEW)
and other related frameworks that account for sustainable development have
been conceived to provide an alternative to the Gross Domestic Product,
which does not capture human welfare in its calculations. This system
weights personal expenditures within a population with an index of income
inequality and a set of factors are then added or subtracted to this monetary
value. Monetary analysis of sustainability does not value the variety of
sustainability issues especially those that cannot be measured as a product
or service in today’s markets (Gasparatos, et al., 2008).
Physical Measures
Physical measures of sustainability use thermodynamic concepts in their
calculations. Two physical approaches to measuring sustainability are
exergy, and emergy. These concepts are derived from the second law of
thermodynamics which states that a closed system with constant mass and
no energy inputs tends toward higher entropy or disorder. For instance, a
piece of wood that is the product of many years of complex tree growth
releases energy (light and heat in the flame) when burned, and becomes
carbon ash, smoke, gases, and water vapor. This means that as properties
within a system such as mass, energy, and chemical concentrations degrade
(decompose) over time or burn, they also make available useful energy
(exergy) for work. Ecosystems and human economies function under this
second law, but they can use external energy (the sun) to maintain or
increase energy supplies.
Emergy is the amount of energy of one kind (solar) that has been used
directly or indirectly (through a transformation process) to make a service
or a product of one type and it is expressed in units of (solar energy)
emjoule. It can be thought of as a measure of all the entropy that has been
produced over the whole process of creating a given product or service
(Brown and Ulgiati, 2002). An example is the process of fossil fuel
creation: solar energy was used by plants to grow and is stored in the
complex molecular structures that held the plants together, when those
plants died they decomposed and were buried over time under the changing
earth, and the energy was concentrated into fossil fuels. Emergy, thus,
allows us to account for all the environmental support needed by human
and eco-systems or inputs.
Measures of energy inputs are transformed to emergy by use of a factor that
represents the amount of environmental work needed to produce a product
or provide a service. The emergy flows within a system include renewable
resources (sunlight, rain, wind, agricultural production, timber harvest,
etc.), non-renewable production (fossil fuels, metals, minerals, soils), and
imports/exports. A sustainable system would have a net positive (or zero)
emergy flow across its boundary (Mayer, et al., 2004). Emergy evaluations
have been used, for instance, to quantitatively demonstrate that renewable
energy plants had higher sustainability compared to thermal plants (Brown
and Ugliati, 2002).
Exergy can be defined as the maximum work that can be extracted from a
system as it moves to thermodynamic equilibrium with a reference state, as
in the example of burned wood above. It has been used to study efficiency
of chemical and thermal processes. This represents an entropy-free form of
energy that is a measure of its usefulness, quality or potential to make
change. Exergy accounting provides insights into the metabolism of a
system and its effect on the environment using a common denominator. It
can address energy utilization, be used for design and analysis of energy
systems and to quantify waste and energy losses reflecting resource use.
Exergy can account for an economic component, labor input, and impact of
Comparison of Measures
So far we highlighted three categories for measures of sustainability —
ecological, economic, and physical — and provided a few examples.
Sustainability measures is an evolving field of study and the metrics are
innumerable. Ecological measures include indicators that try to measure the
sustainability of the ecosystem as a whole. Economic metrics use monetary
measures and try to put a price on the environment and its services. They
are valued based on currency, which is an anthropocentric value, meaning it
is significant only to humans. They account only for human welfare to the
extent that it depends on nature to survive. They do not account for the
effect on an ecosystem as a whole, including plants and animals. Physical
metrics are closely tied to thermodynamics and energy, and are generally
expressed in units of energy.
Sustainability indicators are needed to improve our understanding of the
nature of human demands on ecosystems and the extent to which these can
be modified. Society uses resources for physical and social infrastructure
and continually increases its needs due to population growth which is made
possible by changing the way we grow and produce food, thus manipulating
the food web. Some of these economic metrics are closely tied to social
sustainability metrics as well and try to account for the social welfare of a
population. Overall, while physical tools can capture certain environmental
and economic issues, too, they do not address economic issues from the
Same perspective as conventional economic analysis. Moreover, they do not
capture most social issues.
Economic markets do not usually directly value goods and services that
ecological systems provide to human economies and societies. These
ecosystem services include the uptake of carbon dioxide by plants and trees,
purification of water by microorganisms, enrichment of soil through
degradation of plant and animal materials, and rainfall that provides
irrigation (see Constanza, et al., 1997). Also economists do not agree on the
degree of substitutability between natural and man-made capital. This
concept of substitutability means that natural capital such as 100 year old
(“old forest”) trees used to build homes and furniture can be replaced by
replanting fast-growing trees and provide the same value (Pearce, 1993).
Technology also transforms the use of resources for instance by making
them more readily available and more economic. An example of this is the
use of “fracking” to produce natural gas from sources that were difficult to
extract from a decade ago (see Module Environmental Challenges in
Energy, Carbon Dioxide, Air and Water).
Sustainability Indicators and Composite Indices
There is no single indicator that can capture all aspects of sustainability
within complex systems. When we speak of systems, we are referring to
institutions, cities, regions, or nations. However, a group of indicators could
be selected and analyzed under certain criteria that will better represent this
type of system. An indicator represents a particular operational attribute of
a system such as overall energy reduction, a GHG gas emissions inventory,
what percentage of people commute by public transit, or percentage of
people with a college degree. These are measured or observed at different
times, locations, populations or combinations thereof. The Figure
Information Pyramid represents the relationship between all these
measures.
A group of indicators can then be evaluated using a composite
indicator/index (CI) or rating. CIs stand at the top of an information
pyramid where primary data lies at the base, followed by analyzed data,
then indicators, and topped by indices. A composite indicator is formed by
the compilation of various individual indicators into one index based on an
underlying model. (Nardo, et al., 2005). An example is the Leadership in
Energy and Environmental Design (LEED) which is a green building
certification system developed by the U.S. Green Building Council
(USGBC), It accounts for a large variety of building attributes that
contribute to a building being considered “sustainable” such as building
materials, location, landscape, energy usage, access to alternative
transportation and so on. The final result is a numerical rating for the
building that is then associated with a certain certification level (Certified,
Silver, Gold, Platinum). This kind of system is most widely accepted and
valued when a peer-review is conducted to determine what weights should
be given to each attribute. When the USGBC decided to update its rating
system because it did not accurately reflect the values of its members, it
underwent review through its various committees.
Sometimes, when you have a lot of different measures that use different
units you do not want to aggregate them together into one number. In this
case, a multi-criteria assessment (MCA) can be used where constituent
indicators are not aggregated into a single index. Multi-criteria analysis
(similar name, different context) can be used as a tool to establish weights
for several criteria, without requiring that all data be converted into the
Same units (Hermann, 2007). There are several multi-criteria evaluation
methods that can be used for this. These methods may either be data-driven
(bottom-up) when high-quality data is available or theory driven (top-down)
when data is available for only one of the aspects. A broader review of this
Many industry sectors are developing frameworks or rating systems that
provide ways to report and measure sustainability. Two examples are
discussed here.
The Global Reporting Initiative (GRI) provides a system for organizations
to publish their sustainability performance. Its purpose is to provide
transparency and accountability for stakeholders and to be comparable
among organizations. It is developed in an international, multi-stakeholder
process and it is continuously improved. An organization determines which
indicators from among those proposed it will report. However, no overall
index or scores are reported. There is also usually a narrative portion to the
report (Global Reporting Initiative). The indicators are broken down in
environmental, economic and social performance indicators. Each area has
core indicators with some additional indicators that may be used based on
the organization’s choice.
The American Association of Higher Education (AASHE), is the lead
organization in North America for sustainability in colleges and
universities. One of their major projects has been the development of the
Sustainability Tracking, Assessment and Rating System (STARS). This is a
voluntary, self-reporting framework that is to be used to measure relative
progress of universities and colleges as they work toward sustainability.
STARS was developed using a collaborative process that involved input
from many institutions. In 2008, a pilot study of 66 institutions was
conducted to test the viability of the system and STARS version 1.0 was
released in January 2010 with many schools reporting by January 2011. The
credits are given in three categories of equal weight — education and
research; operations; planning, administration and engagement. Each credit
is given a weight based on the extent to which the credit contributes to
improved environmental, financial and social impacts, and whether there
are educational benefits associated with the achievement of this credit and
the breadth of that impact. The result is a composite indicator, with
transparent individual scoring. Schools participating in STARS will use an
on-line reporting tool which makes the results publicly available.
Depending on the total points achieved, a level of achievement is be
assigned. The STARS rating will be good for three years but a school may
choose to update annually. See Case Study: Comparing Greenhouse Gas
Emissions, Ecological Footprint and Sustainability Rating of a University
for an example of this reporting.
Examples of How an Index is Developed
Krajnc and Glavic (2005) developed a composite sustainable development
index (Icsp) to track economic, environmental and social performance of
company. Economic, environmental, and social sub-indices were calculated
from normalized indicators within each sector. To calculate normalized
indicators, the indicators for each sector, which typically have different
units, were divided by the value in time (year) with its average value of all
the time in the years measured. Alternatively, they can be normalized by
using maximum and minimum values or target values. The Analytic
Hierarchy Process was used to determine the weights of the environmental
indicators. This is a multi-attribute decision model. The steps are:
1. Setting the problem as a hierarchy with the top being the objective of
the decision and lower levels consist of the criteria used at arriving at
the decision.
2. Pair-wise comparisons between two indicators.
3. Use of a consistency ratio to check the consistency of each judgment.
4. Step-by-step procedure of grouping various basic indicators into the
sustainability sub-index.
5. Sub-indices are combined into the composite sustainable development
index.
The economic, environmental and social measures that were used in this
model are as follows:
Economic Environmental Social
No. of
Sales Total energy consumption occupational
accidents
Economic Environmental Social
No. of non-
Operating ; ;
rofit Water consumption profit
P projects
Investmen
ies oa No. of odor
capital & Production mass
complains
expenditures
Carbon dioxide, nitrous .
; a No. of noise
Net earnings oxides, sulfur dioxide & dust ;
a complaints
emissions
Research
cu alee No. of dust
development Wastewater
complaints
costs
No. of
Number of
Waste for disposal neighbor
employees
complaints
Recycling
Hazardous waste
An analytical tool, called COMPLIMENT, was developed to provide
detailed information on the overall environmental impact of a business
(Hermann, 2007). This tool integrates the concepts of life cycle assessment,
multi-criteria analysis and environmental performance indicators. The
combinations of environmental performance indicators used depend on the
organization and reflect the relevant parts of the production train. The
method includes setting system boundaries, data collection, calculation of
potential environmental impacts and their normalization, aggregation of
impacts using a multi-criteria analysis, the weights per impact category are
multiplied by normalization potential impacts and the results can be added
up for each perspective. The system boundary strives to be cradle-to-grave
(from extraction of resources to disposal) although it may be a cradle-to-
gate (from extraction of resources to completion of production) analysis.
Adoption of any single group of tools means that a certain perspective will
be more highly represented in the sustainability assessment. “The need to
address the multitude of environmental, social, economic issues, together
with intergenerational and intragenerational equity concerns” (Gasparatos,
et al., 2008, p. 306) produces problems that none of the disciplinary
approaches can solve separately. Combining the outputs of biophysical and
monetary tools will result in a more comprehensive sustainability
perspective. The result is that the choice of metrics and tools must be made
based on the context and characteristics that are desired by the analysts
(Gasparatos, et al., 2008). Using a composite indicator or a set of individual
indicators presented together can overcome the problem of using a single
metric to measure sustainability.
Existing indicator-based sustainability assessments vary in the number of
subsystems or assessment areas, the number of levels between subsystem
and indicator, and whether they result in an index (compound indicator) of
the state of the system and subsystems. These would include the ecosystem
or environment, people or economy and society, and possibly institutions.
The more subsystems assigned, the lower the weight given to the
environmental portion. As more indicator systems are developed they
become increasingly complex, yet there is a demand for a simple
presentation that does not erase the complexity. A single indicator with true
significance is not achievable, but by combining indicators into indices the
results are more meaningful.
Representing Results for Multi-Criteria Assessment
Since measuring sustainability does not come down to a simple metric or
few it is useful to use visualization techniques to display the results. One
way to depict sustainability performance is to use a graphical view of
progress, as shown in Figure Visualizing Results of Sustainability below
for the GRI for universities. For each category a mapping of the scores was
created. This appears as a hexagon indicating progress in each area for
which points are achieved.
Environment
Visualizing Results of Sustainability
Assessments Hypothetical graphical
representation of the Environmental
Dimension of the GRI for universities. The
red numbers indicate the percentage of
points achieved within each sub-category
within the category of environment. Source:
D. Fredman adapted from Lozano (2006).
Another example of visualizing sustainability is seen in a framework
developed for universities to use (Troschinetz et al., 2007). Again,
multidimensional sustainability indicators, each having an economic,
environmental and social component are used. The categories are listed in
Figure Sustainability Indicator Triangle. Each indicator was examined
using a sustainability indicator triangle where each corner is delineated as
economic, environmental or social and the indicators are placed within to
the triangle to reflect how well each measures those aspects.
Environmental
Quality of education
Transportation
Economic Health (student)
Economic Health (faculty)
Economic Health (staff)
Economic Health (university)
Water Use
Water Quality
Community and Equity
10. Buildings and Spaces
11, Energy and Air Quality
12. Material Flow
13; Purchasing
SO 500), Sig cos el a pe
Economic Social
Sustainability Indicator Triangle The thirteen
sustainability indicators are placed according to how
well each measures a dimension of sustainability, i.e.
environmental, societal and economic. Source: C.
Klein-Banai adapted from Troschinetz, et al. (2007).
Conclusion
Measuring sustainability is difficult because of the interdisciplinary nature
and complexity of the issues that this concern represents. Methods have
been developed out of the different disciplines that are based in the
ecological, economic, physical and social sciences. When approaching a
measure of sustainability it is important to understand what you will use the
results of that measure for, what the major concerns you want to address
are, and the limits of the system you choose. Often it is more meaningful to
measure progress of the entity you are examining — is it more sustainable
than it was before? It is difficult to compare similar entities (countries,
companies, institutions, even products) due to the complexity and
variability in the data. Using visualization to represent the data is a helpful
way to show the state of sustainability rather than trying to express it in one
number or in a table of numbers.
Review Questions
Exercise:
Problem: What is the difference between data and an index?
Exercise:
Problem: What is the major challenge in measuring sustainability?
Exercise:
Problem:
Give three general categories of indicators that are used for measuring
sustainability and provide one example of each.
Exercise:
Problem:
Why is it important to have experts provide input to rating systems?
References
Brown, M.T. & Ulgiati, S. (2002). Emergy evaluations and environmental
loading of electricity production systems. Journal of Cleaner Production,
10, 321-334. doi:10.1016/S0959-6526(01)00043-9
Constanza, R., d'Arge, R., de Groot, R., Farber, S., Grasso, R., Hannon, B.,
et al. (1997). The value of the world's ecosystem services and natural
capital. Nature, 387, 253-260.
Dalal-Clayton, B. & Bass, S. (2002). Sustainable development strategies: A
resource book. London: Earthscan Publications Ltd.
Gasparatos, A., El-Haram, M., & Horner, M. (2008). A critical review of
reductionist approaches for assessing the progress towards sustainability.
Environmental Impact Assessment Review, 28, 286-311.
doi:10.1016/j.eiar.2007.09.002
Hammond, A., Adriaanse, A., Rodenburg, E., Bryant, D., & Woodward, R.
(1995). Environmental indicators: a systematic approach to measuring and
reporting on environmental policy performance in the context of sustainable
development. World Resources Institute. Retrieved March 7, 2011, from
Hermann, B.G., Kroeze, C., & Jawjit, W. (2007). Assessing environmental
performance by combining life cycle assessment, multi-criteria analysis and
environmental performance indicators. Journal of Cleaner Production, 15,
1878-1796. doi:10.1016/j,jclepro.2006.04.004
Krajnc, D. & Glavic, P. (2005). A model for integrated assessment of
sustainable development. Resources Conservation & Recycling, 43, 189-
203.
Lele, S. & Norgaad, R.B. (1996, April). Sustainability and the scientist's
burden. Conservation Biology, 10, 354-365. doi 10.1046/j.1523-
1739.1996.10020354.x
Lozano, R. (2006). A tool for graphical assessment of sustainability in
universities. Journal of Cleaner Production, 14, 963-972. doi:
10.1016/j.jclepro.2005.11.041
Mayer, A.L., Thurston, H.W. & Pawlowski, C.W. (2004). The
multidisciplinary influence of common sustainability indices. Ecological
Environment, 2, 419-426. doi:10.1890/1540-
9295(2004)002[0419:TMIOCS ]2.0.CO;2
Nardo, M., Saisana, M., Saltelli, A, Tarantola S., Hoffman, A. &
Giovannini, E. (2005). Handbook on constructing composite indicators:
Methodology and user guide (STD/DOC (2005)3). Paris: OECD Statistics
Directorate. Retrieved February 26, 2011, from
http://www.oecd.org/dataoecd/37/42/42495745.pdf
Odum, H.T. (1996). Environmental Accounting, Emergy, and
Environmental Decision Making. New York: John Wiley & Sons, Inc.
Pearce, D.W. & G.D. Atkinson (1993). Capital theory and the measurement
of sustainable development: an indicator of “weak” sustainability.
Ecological economics, 8, 103-108.
Rees, W.E. & Wackernagel, M. (1996). Urban ecological footprints: why
cities cannot be sustainable and why they are a key to sustainability.
Enviromental Impact Assessment Review, 16, 223-248.
Reporting Framework Overview. (n.d.). Global Reporting Initiative.
Retrieved August 21, 2011, from
http://www. globalreporting.org/Reporting Framework/Reporting Framework
Overview/
Sahely, H.R., Kennedy, C.A. & Adams, B.J. (2005). Developing
sustainability criteria for urban infrastructure systems. Canadian Journal of
Civil Engineering,32, 72-85. doi: 10.1139/104-072
Troschinetz, A.M., Mihelcic, J.R., & Bradof, K.L. (2007). Developing
Sustainability Indicators for a University Campus. International Journal of
Engineering Education, 23, 231-241.
Glossary
Carrying Capacity
The maximum population that a given environment can sustain.
Ecosystem
All living organisms and non-living things that exist and interact in a
certain area at the same time.
Ecosystem Goods and Services
An essential service an ecosystem provides that supports life and
makes economic activity possible. For example, ecosystems clean air
and water naturally, recycle nutrients and waste generated by human
economic activity.
Emergy
The amount of energy of one kind (solar) that has been used directly or
indirectly (through a transformation process) to make a service or a
product as one type and it is expressed in units of (solar) emjoule.
Emjoule
The unit of emergy or emergy joule. Using emergy, sunlight, fuel,
electricity, and human service can be put on a common basis by
expressing each of them in the emjoules of solar energy that is required
to produce them. If solar emergy is the baseline, then the results are
solar emjoules (abbreviated seJ). Sometimes other baselines such as
coal emjoules or electrical emjoules have been used but in most cases
emergy data are given in solar emjoules.
Entropy
The degree of disorder in a substance, system or process as in the
second law of thermodynamics that states that the make-up of energy
tends to change from a more-ordered state to a less-ordered state,
whereby increasing entropy.
Exergy
The maximum work that can be extracted from a system as it moves to
thermodynamic equilibrium with a reference state.
Indicator
A variable equal to an operational representation of an attribute of a
system.
Indicator-Based Systems
Systems that use quantitative measures of economic progress, social
welfare, or environmental activity that can be interpreted to explain the
state of that system. Examples of these are gross domestic product,
greenhouse gas emissions, and the unemployment rate.
Maximum Sustainable Yield (MSY)
An outgrowth of carrying capacity and the goal is to reach the
maximum amount of resource extraction while not depleting the
resource from one harvest to the next.
Narrative Assessments
Descriptive documentation of a program, plan, or project.
Quantitative Data
Information that can be quantified numerically such as tons of waste,
gallons of gasoline, and gallons of wastewater.
Resilience
The ability of an ecological community to change in response to
disturbance and the degree or time needed for that system that provides
desirable to go back to its original state.
Footprinting: Carbon, Ecological and Water
Footprinting: Carbon, Ecological and Water
Learning Objectives
After reading this section, students should be able to
¢ understand what an environmental footprint is and its limitations
¢ conduct some basic footprinting calculations
¢ calculate and explain their own footprint
Basic Concepts of Footprinting
What is a common measure of the impact of an individual, institution, region or
nation? This can be done by measuring the “footprint” of that entity. When
discussing climate change and sustainability the concepts of carbon footprint and
ecological footprint are often used. Understanding how these footprints are
derived is important to the discourse as not all calculations are equal. These
footprints can be calculated at the individual or household level, the institutional
level (corporation, university, and agency), municipal level, sub-national, national
or global. They are derived from the consumption of natural resources such as raw
materials, fuel, water, and power expressed in quantities or economic value. The
quantity consumed is translated into the footprint by using conversion factors
generally based in scientific or economic values.
Note:What is Your Carbon Footprint?
There are many personal calculators available on the internet. Here are a few to
try:
e EPA Household Emissions Calculator
e Ecological Footprint
e Earth Day Network Footprint
¢ Cool Climate Network (UC Berkeley)
¢ Carbon Footprint
This chapter will discuss three types of footprints — ecological, carbon and water —
and the methodologies behind them. Although efforts have been made to
standardize the calculations comparisons must be approached with caution.
Comparing individual, institutional or national footprints that are calculated by the
same method can be helpful in measuring change over time and understanding the
factors that contribute to the differences in footprints.
Ecological Footprint
Concept
The Merriam-Webster Dictionary defines footprint as:
1. an impression of the foot on a surface;
2. the area on a surface covered by something
Similarly, the ecological footprint (EF) represents the area of land on earth that
provides for resources consumed and that assimilates the waste produced by a
given entity or region. It is a composite index (see Module Sustainability Metrics
and Rating Systems) that represents the amount of biologically productive land
and water area required to support the demands of the population in that entity or
region The EF is beneficial because it provides a single value (equal to land area
required) that reflects resource use patterns (Costanza, 2000). The use of EF in
combination with a social and economic impact assessment can provide a measure
the “hidden” environmental costs of consumption that are not captured by
techniques such as cost-benefit analysis and environmental impact (Venetoulis,
2001). Using the ecological footprint, an assessment can be made of from where
the largest impact comes (Flint, 2001).
Next, we will discuss the how an EFF is calculated.
Methodology
The ecological footprint methodology was developed by William Rees and Mathis
Wackernagel (1996), and consists of two methodologies:
1. Compound calculation is typically used for calculations involving large
regions and nations and is shown in Figure Compound Calculation Steps for
Ecological Footprint Analysis. First, it involves a consumption analysis of
over 60 biotic resources including meat, dairy produce, fruit, vegetables,
pulses, grains, tobacco, coffee, and wood products. That consumption is then
divided by biotic productivity (global average) for the type of land (arable,
pasture, forest, or sea areas) and the result represents the area needed to
sustain that activity. The second part of the calculation includes energy
generated and energy embodied in traded goods. This is expressed in the area
of forested land needed to sequester CO, emissions from both types of
energy. Finally, equivalence factors are used to weight the six ecological
categories based on their productivity (arable, pasture, forest, sea, energy,
built-up land). The results are reported as global hectares (gha) where each
unit is equal to one hectare of biologically productive land based on the
world's average productivity. We derive sub-national footprints based on
apportioning the total national footprint between sub-national populations.
The advantage of this method is that it captures many indirect of effects of
consumption so the overall footprint is more accurate.
2. Component-based calculation resembles life-cycle analysis in that it
examines individual products and services for their cradle-to-grave resource
use and waste, and results in a factor for a certain unit or activity. The
footprint is typically broken down into categories that include energy,
transportation, water, materials and waste, built-up land, and food. This
method is better for individuals or institutions since it accounts for specific
consumption within that entity. However, it probably under-counts as not all
activities and products could practically be measured or included. It also may
double-count since there may be overlap between products and services.
Consumption, ton = production— exports + imports
Biotic
resources
including
those derived
from them
Divide by
biotic Land, hectare = Consumption, ton
productivity land to produce resource + land to absorb waste, hectare/ton
Screen for
nontiha: arable forest es pasture
counting
Addin energy generated and energy embodied in traded
goods expressed as area for forested land to sequester + energy
CO, emissions from all energy
Sum each EF = Aa + SFf + 3Ss + SPp + SSs + SBb + SEe where
— EF = ecological footprint in global hectares (gha)
over all = ecological footprintin giodal nectares (gna
resources, A= arableland, hectares
multiply by F = forest land, hectares
+ snag S= sea area, hectares
factor and
total P = pasture land, hectares
B= built up land, hectares (area of roads, pavement, buildings)
E= energy land, hectares
a, f, s, p, e = equivalence factor for each respective type of land
Compound Calculation Steps for Ecological Footprint Analysis Figure
shows the compound calculation steps for ecological footprint analysis.
Source: C. Klein-Banai.
What the Results Show
When looking at the sub-national level, it is useful to be able to examine different
activities that contribute to the footprint such as energy, transportation, water,
waste, and food. In both types of calculations, there is a representation of the
energy ecological footprint. We utilize conversion factors that account for direct
land use for mining the energy source and the land required to sequester any
carbon emitted during combustion, construction, or maintenance of the power
source. It should be noted that no actual component-based calculations have been
done for nuclear power. The practice has been to consider it the same as coal so as
to account for it in some way. A discussion of the merits of this method can be
found in Wackernagel et al. (2005).
Transportation is another activity that can be examined at the sub-national level.
The transportation footprint maybe considered part of the energy footprint, or
separately, but is basically based on the energy consumption for transportation. It
may also include some portion of the built-up land.
The hydroprint, or water-based footprint, measures the amount of water consumed
in comparison to the amount of water in the land catchment system for the
geographical area being footprinted. It can represent whether the entity is
withdrawing more or less water than is naturally supplied to the area from rainfall.
The wasteprint, or waste-based footprint, is calculated using commonly used
component-based factors that have been calculated and compiled in a number of
publications and books. Food production requires energy to grow, process and
transport, as well as land for growing and grazing. The factors are derived using
the compound calculation for a certain geographical area. See Case Study:
Comparing Greenhouse Gas Emissions, Ecological Footprint and Sustainability
Rating of a University for an example of this kind of ecological footprint analysis.
This kind of analysis can show us how a nation, region, organization, or
individual uses the planets resources to support its operation or life style, as well
as what activities are the primary contributors to the footprint. In the next section,
we will look at some national footprints.
Ecological Footprint Comparisons
|e LIVING PLANET REPORT 2010 €) Read the whole report |
ECOLOGICAL FOOTPRINT INDEX conv ttmu | emmer
In 2007, people used the equivalent of 1.5 planets in 2007 to
support their activities
The Ecological Footprint measures the biologically productive area that people
use for provision of renewable resources, occupy with infrastructure, or require
for absorption of CO2 wastes.
Search Country a gy Locate me!
Select & zoom
aah
10
Fitter
2 © Show All
© Carbon
4.0 (>) Grazing
© Forest
2.0 ©) Fishing
©} Cropland
SG © Built-up Land
ovat, SS se wee eae apes eat
i sateen he bs ag
Sa ~~ Phy, Ra
2g
Ecological Footprints of Select Nations Graph shows the
ecological footprints of select nations. The bars show average EF in
global hectares per person for each nation. Each color on the bar
represents the different types of land. Source: © 2010 WWE
~ figure under CC BY: SA 3.0 License
The Living Planet Report prepared by the World Wildlife Fund, the Institute of
Zoology in London, and Wackernagel’s Global Footprint Network reports on the
footprints of various nations. Figure Ecological Footprints of Select Nations
displays the footprint of several nations as shown in the report. The bars show
average EF in global hectares per person for each nation. Each color on the bar
represents the different types of land. Here we see that the United Arab Emirates
has the largest footprint of 10.2 gha per person, with the majority of its footprint
due to carbon (same as energy land described above). Whereas Latvia has the
lowest footprint displayed at 6.0 gha per person, with the majority of its footprint
due to forestland.
Close
United States of America
« United Kingdom Uruguay »
S Carbon
5-57 gha / ard
Graci
=] O.i4 gha / 84th
Forest
1.03 gha / 7th
r=) Fishing
0.1 gha / Gard
@ Cropland
1.08 gha / 17th
C=) Built-up Land
0.07 gha / 54th
‘Total
7-99 gha / 5th
i
=
F
:
LE
United States’ Ecological Footprint
Figure shows the United States’
Ecological Footprint compared to the
global average. Source: © 2010 WWE
(panda.org). Some rights reserved. Living
Planet Report, 2010, figure under CC BY-
SA 3.0 License
Figure United States’ Ecological Footprint shows the national footprint in 2007 of
the United States as 7.99 gha per person both with a bar display and with specific
metrics on the right that show the exact footprint and the United States’ ranking
among all nations in the report (e.g. carbon is 5.57 gha and ranks 3 largest
overall). The bar to the left expresses the world average. The United States’
footprint of 7.99 gha stands in contrast to the earth's global biocapacity of 1.8 gha
per person. Globally, the total population’s footprint was 18 billion gha, or 2.7 gha
per person. However, the earth’s biocapacity was only 11.9 billion gha, or 1.8 gha
per person. This represents an ecological demand of 50 percent more than the
earth can manage. In other words, it would take 1.5 years for the Earth to
regenerate the renewable resources that people used in 2007 and absorb CO,
waste. Thus, earth’s population used the equivalent of 1.5 planets in 2007 to
support their lives.
Carbon Footprint
Since climate change (see Chapter Climate and Global Change) is one of the
major focuses of the sustainability movement, measurement of greenhouse gases
or carbon footprint is a key metric when addressing this problem. A greenhouse
gas emissions (GHG) inventory is a type of carbon footprint. Such an inventory
evaluates the emissions generated from the direct and indirect activities of the
entity as expressed in carbon dioxide equivalents (see below). Since you cannot
manage what you cannot measure, GHG reductions cannot occur without
establishing baseline metrics. There is increasing demand for regulatory and
voluntary reporting of GHG emissions such as Executive Order 13514, requiring
federal agencies to reduce GHG emissions, the EPA’s Mandatory GHG Reporting
Rule for industry, the Securities and Exchange Commission’s climate change
Commitment (ACUPCC) for universities, ICLEI for local governments, the
California Climate Action Registry, and numerous corporate sustainability
reporting initiatives.
Scoping the Inventory
The first step in measuring carbon footprints is conducting an inventory is to
determine the scope of the inventory. The World Business Council for Sustainable
Development (WBCSD) and the World Resource Institute (WRI) defined a set of
accounting standards that form the Greenhouse Gas Protocol (GHG Protocol).
This protocol is the most widely used international accounting tool to understand,
quantify, and manage greenhouse gas emissions. Almost every GHG standard and
program in the world uses this framework as well as hundreds of GHG inventories
prepared by individual companies and institutions. In North America, the most
widely used protocol was developed by The Climate Registry.
The GHG Protocol also offers developing countries an internationally accepted
management tool to help their businesses to compete in the global marketplace
and their governments to make informed decisions about climate change. In
general, tools are either sector-specific (e.g. aluminum, cement, etc.) or cross-
sector tools for application to many different sectors (e.g. stationary combustion
or mobile combustion).
C02 SFe CH4 N20 HFCs PCFs
Scopes of a Greenhouse Gas Emissions Inventory Figure shows the three
scopes of a greenhouse gas emissions inventory. Source: New Zealand
The WRI protocol addresses the scope by which reporting entities can set
boundaries (see Figure Scopes of a Greenhouse Gas Emissions Inventory). These
standards are based on the source of emissions in order to prevent counting
emissions or credits twice. The three scopes are described below:
¢ Scope 1: Includes GHG emissions from direct sources owned or controlled
by the institution — production of electricity, heat or steam, transportation or
materials, products, waste, and fugitive emissions. Fugitive emissions are
due to intentional or unintentional release of GHGs including leakage of
refrigerants from air conditioning equipment and methane releases from farm
animals.
¢ Scope 2: Includes GHG emissions from imports (purchases) of electricity,
heat or steam — generally those associated with the generation that energy.
¢ Scope 3: Includes all other indirect sources of GHG emissions that may
result from the activities of the institution but occur from sources owned or
controlled by another company, such as business travel; outsourced activities
and contracts; emissions from waste generated by the institution when the
GHG emissions occur at a facility controlled by another company, e.g.
methane emissions from landfilled waste; and the commuting habits of
community members.
Depending on the purpose of the inventory the scope may vary. For instance, the
EPA mandatory reporting requirements for large carbon dioxide sources require
reporting of only Scope 1 emissions from stationary sources. However, many
voluntary reporting systems require accounting for all three scopes, such as the
ACUPCC reporting. Numerous calculator tools have been developed, some
publicly available and some proprietary. For instance many universities use a tool
called the Campus Carbon Calculator developed by Clean Air-Cool Planet, which
is endorsed by the ACUPCC. Numerous northeastern universities collaborated to
develop the Campus Carbon Calculator and the calculator has been used at more
than 200 campuses in North America. It utilizes an electronic Microsoft Excel
workbook that calculates estimated GHG emissions from the data collected.
Methodology
GHG emissions calculations are generally calculated for the time period of one
reporting GHG emissions. It is necessary to determine what the baseline year is
for calculation. This is the year that is generally used to compare future increases
or decreases in emissions, when setting a GHG reduction goal. The Kyoto
Protocol proposes accounting for greenhouse gas emissions from a baseline year
of 1990. Sometimes calculations may be made for the current year or back to the
earliest year that data is available.
Steps for Preparing a GHG Emissions Report Figure
shows the required steps to take when preparing a GHG
emissions report. Source: C. Klein-Banai
Next, the institutional or geographic boundaries need to be defined. Also, the
gases that are being reported should be defined. There are six greenhouse gases
defined by the Kyoto Protocol. Some greenhouse gases, such as carbon dioxide,
occur naturally and are emitted to the atmosphere through natural and
anthropogenic processes. Other greenhouse gases (e.g. fluorinated gases) are
created and emitted solely through human activities. The principal greenhouse
gases that enter the atmosphere because of human activities are:
¢ Carbon Dioxide (CO2): Carbon dioxide is released to the atmosphere
through the combustion of fossil fuels (oil, natural gas, and coal), solid
waste, trees and wood products, and also as a result of non-combustion
reactions (e.g. manufacture of cement). Carbon dioxide is sequestered when
plants absorb it as part of the biological carbon cycle.
e Methane (CH4): Methane is emitted during the production and transport of
coal, natural gas, and oil. Methane emissions also come from farm animals
and other agricultural practices and the degradation of organic waste in
municipal solid waste landfills.
Nitrous Oxide (N2O): Nitrous oxide is emitted during agricultural and
industrial activities, and combustion of fossil fuels and solid waste.
Fluorinated Gases: Hydrofluorocarbons, perfluorocarbons, and sulfur
hexafluoride are synthetic, powerful greenhouse gases that are emitted from
a variety of industrial processes. Fluorinated gases are sometimes used as
substitutes for ozone-depleting substances (i.e. Chlorofluorocarbons (CFCs),
hydrochlorofluorocarbon (HCFCs), and halons). CFCs and HCFCs are gases
comprised of chloride, fluoride, hydrogen, and carbon. Halons are elemental
gases that include chlorine, bromine, and fluorine. These gases are typically
emitted in smaller quantities, but because they are potent greenhouse gases,
they are sometimes referred to as High Global Warming Potential gases
(“High GWP gases”).
Each gas, based on its atmospheric chemistry, captures different amounts of
reflected heat thus contributing differently to the greenhouse effect, which is
known as its global warming potential. Carbon dioxide, the least capture efficient
of these gases, acts as the reference gas with a global warming potential of 1.
Table Global Warming Potentials shows the global warming potential for the
various GHGs.
Gas GWP
CO2 1
CH4 21
N20 310
HFC-23 11,700
HFC-32 650
HFC-125 2,800
Gas GWP
HFC-134a 1,300
HFC-143a 3,800
HFC-152a 140
HFC-227ea 2,900
HFC-236fa 6,300
HFC-4310mee 1,300
CF4 6,500
C2F6 9,200
C4F10 7,000
C6F14 7,400
SF6 23,900
Global Warming Potentials Source: C. Klein-Banai created table using data from
Climate Change 2007: The Physical Science Basis: Contribution of Working
Climate Change, Cambridge University Press, section 2.10.2
GHG emissions cannot be easily measured since they come from both mobile and
stationary sources. Therefore, emissions must be calculated. Emissions are usually
calculated using the formula:
Equation:
AxF,=E
where A is the quantification of an activity in units that can be combined with
emission factor of greenhouse gas g (Fg) to obtain the resulting emissions for that
gas (Eg).
Examples of activity units include mmbtu (million British Thermal Units) of
natural gas, gallons of heating oil, kilowatt hours of electricity, and miles traveled.
Total GHG emissions can be expressed as the sum of the emissions for each gas
multiplied by its global warming potential (GWP). GHG emissions are usually
reported in metric tons of carbon dioxide equivalents (metric tons CO>-e):
Equation:
GHG = ) | E,GWP,
Eg is usually estimated from the quantity of fuel burned using national and
regional average emissions factors, such as those provided by the US Department
of Energy’s Energy Information Administration.
Emission factors can be based on government documents and software from the
U.S. Department of Transportation, the U.S. Environmental Protection Agency.
(EPA), and the U.S. Department of Energy, or from specific characteristics of the
fuel used — such as higher heating value and carbon content. Scope 3 emissions
that are based on waste, materials, and commuting are more complex to calculate.
Various calculators use different inputs to do this and the procedures are less
standardized. See Case Study: Comparing Greenhouse Gas Emissions, Ecological
of calculations.
Greenhouse gas emissions inventories are based on standardized practice and
include the steps of scoping, calculating, and reporting. They are not based on
actual measurements of emissions, rather on calculations based on consumption of
greenhouse gas generating materials such as fossil fuels for provision of energy
and transportation or emissions from waste disposal. They can be conducted for
buildings, institutions, cities, regions, and nations.
Carbon Footprint Comparisons
Comparison of carbon footprints reveal interesting differences between countries,
particularly when compared to their economic activity. The World Bank tracks
data on countries and regions throughout the world as part of their mission to
“fight poverty...and to help people help themselves and their environment”
(World Bank, 2011). Table Gross Domestic Product (GDP) and Emissions for
Select Regions, 2007 shows the results for GHG emissions and gross domestic
product for various regions of the world. It is interesting to note that the United
States’ emissions per capita (19.34 mt e-CO,) are more than four times the world
average. The United States’ economy makes up one fourth of the world GDP.
CO2 GDP
CO2 emissions GDP per
emissions (metric (current Capita
Country (metric tons per US$ (current
Name ton) capita) millions) USS)
East Asia &
Paciiic (aul 10,241,229 4.76 $11,872,148 $5,514
income
levels)
Europe &
col | 6 eons 772 $20,309,468 $23,057
(all income
levels)
Latin
America &
Caribbean 1,622,809 2.87 $3,872,324 $6,840
(all income
levels)
Latin
America &
Caribbean 1,538,059 2./5 $3,700,320 $6,610
(developing
only)
CO2 GDP
CO2 emissions GDP per
emissions (metric (current Capita
Country (metric tons per US$ (current
Name ton) capita) millions) USS)
Least
developed
countries: 185,889 0.23 $442,336 $553
UN
classification
Middle East
& North
Africa (all 1,992,795 5.49 $1,924,470 $5,304
income
levels)
South Asia 1,828,941 1.20 $1,508,635 $991
Sub-Saharan
souoee cas 684,359 0.86 $881,547 $1,102
income
levels)
eee 5,832,194 19.34 $14,061,800 $46,627
States
World 30,649,360 4.63 $55,853,288 $8,436
Gross Domestic Product (GDP) and Emissions for Select Regions, 2007Table
shows the GDP and emissions for select regions in 2007. Source: C. Klein-Banai
created table using data from The World Bank, "World Development Indicators"
Water Footprint
The water footprint of production is the volume of freshwater used by people to
produce goods, measured over the full supply chain, as well as the water used in
households and industry, specified geographically and temporally. This is slightly
different from the hydroprint described above which simply compares the
consumption of water by a geographic entity to the water that falls within its
watershed. If you look at the hydrologic cycle (see module Water Cycle and Fresh
Water Supply), water moves through the environment in various ways. The water
footprint considers the source of the water as three components:
e Green water footprint: The volume of rainwater that evaporates during the
production of goods; for agricultural products, this is the rainwater stored in
soil that evaporates from crop fields.
¢ Blue water footprint: The volume of freshwater withdrawn from surface or
groundwater sources that is used by people and not returned; in agricultural
products this is mainly accounted for by evaporation of irrigation water from
fields, if freshwater is being drawn.
¢ Grey water footprint: the volume of water required to dilute pollutants
released in production processes to such an extent that the quality of the
ambient water remains above agreed water quality standards.
The water footprint of an individual is based on the direct and indirect water use
of a consumer. Direct water use is from consumption at home for drinking,
washing, and watering. Indirect water use results from the freshwater that is used
to produce goods and services purchased by the consumer. Similarly, the water
footprint of a business or institution is calculated from the direct and indirect
water consumption.
& LIVING PLANET REPORT 2010 ©) Read the whole report |
WATER FOOTPRINT OF PRODUCTION S22 2053) Eee
The Water Footprint of Production
The Water Footprint of Production is the total volume of freshwater used by
people, either directly or indirectly, in producing goods and services in a
country, specified geographically and temporally.
Search Country Loe gy Locate met
Select & zoom
1400
eae | |
T2939 Filter
800 @ Show All
<>) Blue water
ee) © Green water
400 . Grey water
a LITT
2 ERaeee
We,
~~ Cees ae Op aie ee aa, es
eos a <p <a
S ay ey
Water Footprint of Production of Select Countries Graph
shows the water footprint of production of select countries.
Planet Report, 2010, figure under CC BY-SA 3.0 License
Figure Water Footprint of Production of Select Countries shows the water
footprint of production for several countries as a whole. In this report, due to lack
of data, one unit of return flow is assumed to pollute one unit of freshwater. Given
the negligible volume of water that evaporates during domestic and industrial
processes, as opposed to agriculture, only the grey water footprint for households
and industry was included. This figure does not account for imports and exports it
is only based on the country in which the activities occurred not where they were
consumed.
In contrast, the water footprint of a nation accounts for all the freshwater used to
produce the goods and services consumed by the inhabitants of the country.
Traditionally, water demand (i.e. total water withdrawal for the various sectors of
economy) is used to demonstrate water demand for production within a nation.
The internal water footprint is the volume of water used from domestic water
resources; the external water footprint is the volume of water used in other
countries to produce goods and services imported and consumed by the
inhabitants of the country. The average water footprint for the United States was
calculated to be 2480m?/cap/yr, while China has an average footprint of
700m?/cap/yr. The global average water footprint is 1240m°/cap/yr. As for
ecological footprints there are several major factors that determine the water
footprint of a country including the volume of consumption (related to the gross
national income); consumption pattern (e.g. high versus low meat consumption);
climate (growth conditions); and agricultural practice (water use efficiency)
(Hoekstra & Chapagain, 2007).
Using average water consumption for each stage of growth and processing of tea
or coffee, the “virtual” water content of a cup can be calculated (Table Virtual
Water Content of a Cup of Tea or Coffee). Much of the water used is from rainfall
that might otherwise not be “utilized” to grow a crop and the revenue from the
product contributes to the economy of that country. At the same time, the result is
that many countries are “importing” water to support the products they consume.
Drink Preparation Virtual water content (I/cup)
Standard cup of coffee 140
Coffee Strong coffee 200
Instant coffee 80
Standard cup of tea 34
Tea
Weak tea 17
Virtual Water Content of a Cup of Tea or CoffeeTable shows the virtual water
content for a cup of tea or coffee. Source: C. Klein-Banai created table using data
or Coffee" longdesc="Table shows the virtual water content for a cup of tea or
coffee."
To learn more about other countries’ water footprints, visit this interactive graph.
To calculate your own water footprint, visit the Water Footprint Calculator.
The water footprint reveals that much more water is consumed to make a product
than appears in using a simple calculation. It is not just the water content of the
product but includes all water used in the process to make it and to manage the
waste generated from that process.
Summary
Footprinting tools can be useful ways to present and compare environmental
impact. They are useful because they can combine impacts from various activities
into one measure. However, they have limitations. For instance, in a carbon
footprint or greenhouse gas emissions inventory, many of the “conventional”
environmental impacts such as hazardous waste, wastewater, water consumption,
stormwater, and toxic emissions are not accounted for, nor are the impacts of
resource consumption such as paper, food, and water generally measured. Perhaps
most importantly, certain low-carbon fuel sources (e.g. nuclear power) that have
other environmental impacts (e.g. nuclear waste) are neglected. Finally, the scope
of the emissions inventory does not include upstream emissions from the
manufacture or transport of energy or materials. This suggests that there is a need
to go beyond just GHG emissions analyses when evaluating sustainability and
include all forms of energy and their consequences.
The ecological footprint can be misleading when it is looked at in isolation, for
instance with an urban area, the resources needed to support it will not be
provided by the actual geographic area since food must be “imported” and carbon
offset by natural growth that does not “fit” in a city. However, cities have many
other efficiencies and advantages that are not recognized in an ecological
footprint. When looked at on a national level it can represent the inequities that
exist between countries.
It is interesting to contrast the water and ecological footprints, as well. The water
footprint explicitly considers the actual location of the water use, whereas the
ecological footprint does not consider the place of land use. Therefore it measures
the volumes of water use at the various locations where the water is appropriated,
while the ecological footprint is calculated based on a global average land
requirement per consumption category. When the connection is made between
place of consumption and locations of resource use, the consumer's responsibility
for the impacts of production at distant locations is made evident.
Review Questions
Exercise:
Problem:
Choose a calculator from the box and calculate your own footprint. How
does it compare to the national or global average? What can you do to reduce
your footprint?
Exercise:
Problem:
Discuss what kind of inequities the various footprints represent between
nations and the types of inequities.
Exercise:
Problem:
How might the “food print” of a vegetarian differ from a carnivore?
References
Chambers, N., Simmons, C. & Wackernagel, M. (2000). Sharing Nature’s
Interest: Ecological Footprints as an Indicator of Sustainability. London:
Earthscan Publications Ltd.
Chapagain, A.K. & Hoekstra, A.Y. (2007). The water footprint of coffee and tea
consumption in the Netherlands. Ecological Economics, 64, 109-118.
Constanza, R. (2000). The dynamics of the ecological footprint concept.
Ecological Economics,32, 341-345.
Dawe, G.F.M., Vetter, A. & Martin. S. (2004). An overview of ecological
footprinting and other tools and their application to the development of
sustainability process. International Journal of Sustainability in Higher
Education, 4, 340-371.
Flint, K. (2001). Institutional ecological footprint analysis: A case study of the
University of Newcastle, Australia. International Journal of Sustainability in
Higher Education, 2, 48-62.
Hoekstra, Y. & Chapagain, A. K. (2007). Water footprints of nations: Water use by
people as a function of their consumption pattern. Water Resour Manage, 21, 35-
48.
Klein-Banai, C. (2007). Greenhouse gas inventory for the University of Illinois at
Chicago. UIC GHG Inventory,Retrieved November 21, 2009 from
005-2006.pdf
Rees, W.E. and Wackernagal, M. (1996). Urban ecological footprints and why
cities cannot be sustainable — and why they are a key to sustainability.
Environmental Impact Assessment Review, 16, 223-248.
Venetoulis, J. (2001). Assessing the ecological impact of a university: The
ecological footprint for the University of Redlands. International Journal of
Sustainability in Higher Education, 2, 180-196.
Wackernagel, M., Monfreda, C., Moran, D., Wermer, P., Goldfinger, S.,
Deumling, D., & Murray, M. (2005, May 25). National footprint and biocapacity
accounts 2005: The underlying calculation method. Global Footprint Network.
id=5.
World Bank (2011). About Us. Retrieved September 20, 2011 from
http://g0.worldbank.org/3QT2P1GNHO.
Glossary
Anthropogenic
Relating to or resulting from the influence that humans have on the natural
world.
Cradle-to-Grave
From creation to disposal; throughout the life cycle.
Ecological Footprint (EF)
Represents the area of land on earth that provides for resources consumed
and assimilates the waste produced by a given entity.
Global Warming Potential (GWP)
Each gas, based on its atmospheric chemistry, captures different amounts of
reflected heat thus contributing differently to the greenhouse effect
contributing to its GWP. Carbon dioxide, the least capture efficient of these
gases, acts as the reference gas with a global warming potential of 1.
Gross Domestic Product
The sum of gross value added by all resident producers in the economy plus
any product taxes and minus any subsidies not included in the value of the
products. It is calculated without making deductions for depreciation of
fabricated assets or for depletion and degradation of natural resources.
Sequestered
Removed from the atmosphere
Triple Bottom Line
Accounting for ecological and social performance in addition to financial
performance
Case Study: Comparing Greenhouse Gas Emissions, Ecological Footprint and
Sustainability Rating of a University
Case Study: Comparing Greenhouse Gas Emissions, Ecological
Footprint and Sustainability Rating of a University
How do different measures of sustainability compare when looking at one
institution? This case study compares these different measures for the
University of Illinois at Chicago (UIC). Located just southwest of downtown
Chicago, UIC has 13 colleges serving 27,000 students and 12,000 employees,
with over 100 buildings on 240 acres (97 hectares) of land. The activities of the
faculty, staff and students and the buildings and grounds have an impact on the
sustainability of the institution. This case study will look at the results of the
greenhouse gas emission inventory, ecology footprint, and sustainability rating.
UIC's Greenhouse Gas Emission Inventory-
Regional Mix
Thousands
"Transmission & Distribution Losses
™ Solid Waste
™ Directly Financed Air Travel
™ Student Commuting
™ Faculty / Staff Commuting
®™ Purchased Electricity
2
ra
2
i)
2
3
z
®
nN
°
re)
ww
c
S
~
uv
=
a
=
® Direct Transportation
®™ Other On-Campus Stationary
™ Total UIC Power Plants
2004 2005 2006 2007 2008 2009 2010
Fiscal Year
Greenhouse Gas Emissions Inventory UIC's Greenhouse gas emissions
profile for FY 2004-2010, using the regional mix for purchased electricity.
Source: C. Klein-Banai
Figure Greenhouse Gas Emissions Inventory displays UIC's GHG emissions
profile for seven years. The emissions were calculated using the Campus
Carbon Calculator developed by the not-for-profit organization, Clean Air-Cool
Planet. While this tool has a number of limitations it has been used by many of
the over 670 colleges and universities who are signatory to the American
College and University Presidents Climate Commitment (ACUPCC) to
simplify the emissions inventory profile. The tool is also recommended by the
ACUPCC as a standard method of emissions calculation for United States
universities. It is based on the World Resources Institute (WRI) and World
Business Council for Sustainable Development (WBSCD) Greenhouse Gas
(GHG) Protocol Initiative that developed GHG emissions inventory standards.
UIC's emissions were calculated using the regional average electricity sources
for the electric grid servicing the Chicago area. However, until August of 2009,
UIC purchased electricity from Commonwealth Edison which has a much
lower greenhouse gas emissions factor due to the high percentage of nuclear
power in the Chicago region.
UIC operates two combined heat and power plants. However, the university has
increasingly lowered its production of electricity from natural gas by
purchasing more electricity through block purchases (for defined amounts of
electricity for a certain period of time) due to the relatively low cost of
purchasing electricity as compared to self-generating. This strategy has
increased UIC's emissions as the regional mix has a fair amount of coal-
powered plants providing electricity. Neverthless, a downward trend in
emissions is beginning in spite of the increased electricity purchases between
2009 and 2010. This may be due to overall reduction in energy consumption on
campus, which is reducing the GHG emissions.
Figure Breakdown of UIC's Greenhouse Gas Emissions illustrates the relative
contribution to UIC's 2010 emissions profile, with 77 percent of emissions
coming from buildings (power plants, purchased electricity, and other on-
campus stationary, i.e. natural gas supply to the buildings), 20 percent due to
transportation (campus fleet , commuting to campus, and air travel), and less
than one percent for emissions due to waste sent to the landfill (which
generates methane).
0.4%
& Total UIC Power Plants
@ Other On-Campus Stationary
@ DirectTransportation
®@ Purchased Electricity
@ Faculty / Staff Commuting
®@ Student Commuting
@ Directly Financed Air Travel
0.7%
0.4%
Breakdown of UIC's Greenhouse Gas Emissions Figure shows the
breakdown of UIC's greenhouse gas emissions inventory for the fiscal
year 2010, in metric tons of carbon dioxide equivalents (mt CO>-e).
Total emissions: 354,758 mt CO»-e. Source: C. Klein-Banai
UIC's total emissions for fiscal year 2010 were 354,758 mt CO>-e, which
amounts to 13.14 mt CO>-e per full-time equivalent student enrolled. Table
Comparison of GHG Emissions compares UIC's emissions to those of the city
of Chicago, state of Illinois, and the United States.
GHG emissions, million MT Most Recent Year
Entity CO 2-e Reported
US 6,633.20 2009
GHG emissions, million MT
Entity CO 2-e
Illinois 274.9
Chicago 36.2
UIC 0.4
Most Recent Year
Reported
2003
2005
2010
Comparison of GHG EmissionsSources: C. Klein-Banai created table using
data from UIC Climate Action Plan, Chicago Climate Action Plan, U.S. EPA.
An Ecological Footprint Analysis (EFA) was conducted using data from fiscal
year 2008, including much of the same data used for the GHG emissions
inventory. In addition, water, food, recycling, and built-up land data were used
to calculate the number of global hectares required to provide the resources and
absorb the waste and GHG emissions produced to support UIC's activities. The
results are displayed in Table UIC's Ecological Footprint Using FY 2008 Data.
The total footprint was 97,601 global hectares, on a per capita basis this is
equivalent to 2.66 gha/person. This is in contrast to about 8.00 gha/person
nationally in the United States, although one must use caution in making
comparisons because the scope and methodology of the analysis differ.
Category Global Hectares Percent
Energy 70,916 72.7%
Transportation 12,293 12.6%
Water 139 0.1%
TOTAL, Global Hectares 97,601
100.0%
Category Global Hectares Percent
Materials and waste 11,547 11.8%
Built-up land 172 0.2%
Food 2,933 2.6%
TOTAL, Global Hectares 97,601 100.0%
UIC's Ecological Footprint Using FY2008 DataComposite Indicator:
Sustainability Tracking, Assessment and Rating System. Source: C. Klein-
Bandai.
The STARS system (see module Sustainability Metrics and Rating Systems)
was used to rate UIC. The university received 39.1 points, for a Bronze rating.
The points break down into the categories shown in Table STARS Points
Received by UIC by Category. There are three main categories of points —
Education & Research; Operations; and Planning, Administration &
Engagement. Within each of the categories there are sub-categories such as
Curriculum, Climate, and Coordination & Planning. Within those sub-
categories there are specific strategies that address them, with varying amounts
of points that depend on the assessed weight of each strategy. Each category's
individual percentage score is weighted equally to the others. In addition, four
innovation strategies are available for which an institution can receive one
point. These points are not attributed to a particular category.
% Per
Points Received Possible Category Weight
Pavealon 38.61% 33.33/100
Research
Points
Co-Curricular
Education
Curriculum
Research
Operations
Buildings
Climate
Dining
Services
Energy
Grounds
Purchasing
Transportation
Waste
Water
Planning,
Administration
& Engagement
Coordination
and Planning
Received
11.75
18.89
7.97
15.00
% Per
Possible Category
18.00
59.00
27.00
23.78%
13.00
16.50
8.50
16.50
3.25
7.90
12.00
12.50
10.25
34.91%
18.00
Weight
33.33/100
33.33/100
% Per
Points Received Possible Category Weight
Diversity and
Affordability =D oe
samen 19.75 19.75
Resources
Investment 0.00 16.75
Pane 6.66 8175
Engagement
Innovation 0.00 4.00
STARS Points Received by UIC by CategorySource: C. Klein-Banai with data
from STARS
This reporting system shows that UIC's strengths lie in the areas outside of
operations, which are what is measured with an EFA or GHG emissions
inventory. Most points were gained for Planning, Administration &
Engagement. This rating system can be used to identify specific areas that can
be targeted for advancing sustainability initiatives in a much broader realm than
the other two metric allow. This case study demonstrates the different types of
information and sustainability tracking that can be done using different types of
measures of sustainability. Whether you use one measure or several depends on
the purpose and scope of the sustainability reporting.
References
Klein-Banai, C, Theis, T.L., Brecheisen, T.A. & Banai, A. (2010). A
Greenhouse Gas Inventory as a Measure of Sustainability for an Urban Public
Research University, Environmental Practice, 12, 25-47.
Klein-Banai, C & Theis, T.L. (2011). An urban university's ecological footprint
and the effect of climate change, Ecological Indicators, 11, 857-860.
UIC Office of Sustainability. (2011). State of Sustainability University of
Illinois at Chicago Biennial Report. Retrieved May 30, 2011 from
Food Miles
In this module, you will learn what food miles are and why they are used,
you will compare the strengths and limitations of the use of food miles, and
you will explore the implications of food miles in decision-making
strategies.
Learning Objectives
After reading this module, students should be able to
e understand what food miles are and why they are used.
¢ compare the strengths and limitations of the use of food miles.
e explore the implications of food miles in decision-making strategies.
Introduction
Efforts to explore the impacts of the items on our dinner tables led to the
broad concept of food miles (the distance food travels from production to
consumption) as being a quick and convenient way to compare products.
With increasing globalization, our plates have progressively included food
items from other continents. Previously it would have been too expensive to
transport these products. However, changes to agricultural practices,
transportation infrastructure, and distribution methods now mean that
people in the United States can start the day with coffee from Brazil, have a
pasta lunch topped with Italian cheeses, snack on chocolate from Céte
d'Ivoire, and end with a dinner of Mediterranean bluefin tuna and Thai rice.
However, the globalization that has led to increased availability of these
products comes with associated costs, such as the emission of greenhouse
gases and other pollutants, increased traffic congestion, lack of support for
local economies, less fresh food, and decreased food security. Therefore,
the concept of measuring food miles was meant to provide an easy
comparison of the relative impacts of our food choices.
Many individuals, groups, and businesses today measure or calculate food
miles. But, when Andrea Paxton, a U.K.-based environmental activist,
coined the term in the 1990s the concept of food miles was intended to
encompass more than simply a distance. The point was to broaden
awareness that our food choices have consequences that are often not
apparent. Consumers frequently do not know the histories behind their food
purchases, and markets often cannot supply the information because of the
many production processes and distribution methods used.
While the distance food travels does determine some of the environmental,
social, and economic impacts, there can be other hidden consequences not
so easily measured. Exploration of the utility of food miles in the general
sense of knowing the impacts of our purchasing decisions has resulted in a
broadening awareness of the complexity of globalization. Although
consumers can use the easy-to-compare numbers representing food miles,
that metric cannot reflect all of the impacts of food purchasing decisions.
Calculating Food Miles
In some cases it is easy to use food miles, such as comparing two
watermelons grown using the same methods and both transported by truck
to your store. However, many of our food products contain components
with different origins. In that case, food miles are calculated as a weighted
average to create a single number that takes into consideration the weight
and distance of each item. For example, to calculate the food miles for a
simple fruit salad that contains only apples, bananas, and honey, you need
to know the distance that each ingredient traveled to reach your market and
the relative amount of each product. Figure Food Miles for Fruit Salad
illustrates the food miles for this simple fruit salad.
Food Miles for Fruit Salad The various ingredients in
this simple fruit salad travel different distances to
Illinois' supermarkets. Source. D. Ruez adapated from
TUBS, akarlovic, FirOQ002, and Abrahami
Most of our food from supermarkets is marked with a country or state of
origin. That alone is usually enough to get an estimate of the distance,
especially if the location can be narrowed down by finding out the part of
the country or state that most commonly produces the product. If the fruit
salad in Figure Food Miles for Fruit Salad is being made in Chicago,
Illinois, and the apples are from the state of Washington, the likely origin is
in the center part of the state. The travel distance is approximately 2,000
miles (3,219 km). Bananas from Costa Rica traveled about 2,400 miles
(3,862 km) to Chicago, and there are honey producers only 160 miles (257
km) from Chicago. A simple average of the miles the ingredients traveled
would not take into account that the fruit salad probably would not contain
equal amounts of the three items. If the recipe called for 2 pounds (.9 kg) of
apples, 2 pounds (.9 kg) of bananas, and a % pound (.1 kg) of honey, the
miles would be weighted toward the distances traveled by the fruit: 2080
food miles per pound of fruit salad (or 3,347 km/kg of fruit salad).
Benefits
The benefits of using food miles in evaluating food choices match the three
main categories that represent sustainability: environmental, social, and
economic. All methods of transporting food over long distances, and most
methods used to transport over short distances, involve fossil fuels. Burning
of fossil fuels creates greenhouse gases, which contribute to climate change.
Using fossil fuels also results in the emission of other gases and particulates
that degrade air quality. Longer transportation distances intensify traffic
congestion, resulting in lost productivity, and increase the need for more
extensive infrastructure (such as more highways) that negatively impact the
environment by increasing the amount of impervious cover and by
requiring more natural resources. Increased roadways also encourage
sprawl, leading to more inefficient development patterns. Finally, traffic
congestion and air pollution from driving contribute to an estimated
900,000 fatalities per year worldwide.
Use of food miles is often tied to locavore movements, which emphasizes
consumption of locally-grown food products. Local food is usually fresher,
with harvesting waiting until produce is ripe, and has less processing and
fewer preservatives. Many people think locally-grown food tastes better, but
others chose to be a locavore because it strengthens local cultural identity or
because the safety of the food is being controlled by people who also
consume the products themselves. Eating local foods also promotes food
security because availability and price of imported foods is more dependent
on fluctuating fuel costs and sociopolitical conflicts elsewhere.
The production of food in developing countries, and the subsequent
exporting of those products, has several types of impacts. The
environmental burden of soil degradation, water depletion, and others, are
imposed on developing countries, while more prosperous countries enjoy
the benefits. This can be especially problematic because some developing
countries do not have the policies to require, or the resources to implement,
more environmentally-friendly food production practices. In particular, the
low prices paid to food producers in developing countries do not include
sufficient funds, or requirements, for practices to preserve or restore
ecosystem quality. Moreover, developing countries disproportionately suffer
malnutrition, yet the success of large-scale transport of food encourages
cultivation of products to be exported instead of planting nutritious foods to
be self-sustaining.
Some businesses are embracing the basic concepts of food miles because
transporting food over shorter distances uses less fuel, and is therefore
cheaper. Additionally, food that covers longer distances usually requires
more packaging, which adds to the cost. By focusing on local foods, local
economies are supported. This has led to clearer labeling of food products,
giving consumers the ability to make more informed decisions about their
purchases.
Criticism
Although the concept of food miles is useful, it has been heavily criticized
for being too simplistic. For example, all miles are not created equally. The
consumption of fuel varies by the mode of transportation and the amount
being moved. If you compare the consumption required to move one pound
of a product, ocean freighters are the most efficient of the common
methods, followed by trains, trucks, and finally planes. When a
combination of transportation methods is used, making a comparison with
food miles becomes even more complex. This is especially a problem
because most of us drive a personal vehicle to get our groceries. That means
that it may be more efficient (from a total fuel consumption perspective) to
drive 1 mile (1.6 km) to a local supermarket who imports beef from
Australia, than to drive 40 miles (64 km) to visit a market selling locally-
produced beef.
Food miles also do not take into consideration the variables of production
before the products are transported. Growing outdoors requires different
amounts of energy input than greenhouses. A commonly cited example is
that of tomatoes; heating greenhouses to grow tomatoes in the United
Kingdom consumes much more energy than growing tomatoes in warm
Spain and importing them. Use of chemical fertilizers and pesticides affect
environmental quality and production levels differently than organic
farming. Because soil quality varies, locally-grown foods, in some cases,
require more of the chemical additives. Some areas may have newer
equipment, better climate, increased access to water, or other factors that
determine the overall efficiency of food production. Growing rice in deserts
or oranges in the Arctic would have more environmental impacts than the
transportation of those products from locales where they can be grown more
efficiently (from both an environmental and economic perspective).
Understanding these production variables is critical because several recent
studies have suggested that as much as 80% of greenhouse-gas generation
from food consumption comes from the production phase. See References
for further reading.
There are also benefits to globalization and increased transport of food.
There is now more widespread access to a broader range of food products.
This can lead to increased appreciation for other cultures and greater
international cooperation. Long-distance transport of food products can also
provide jobs to developing nations by giving them access to larger, more
prosperous markets internationally. Jobs and economic incentives from food
production are some of the few widespread opportunities for developing
countries, and these may lead to growth in other economic areas.
Criticism of the use of food miles can be unfairly disapproving of products
that travel long distances. However, simple calculations of food miles have
also been said to underrepresent the importance of travel distances. Most
food is transported with some packaging, and that packaging also requires
energy input for its production and transport. Because products that move
shorter distances usually have less packaging, the difference in calculated
food miles may underestimate the actual environmental impact. Local foods
also require less energy and resource consumption because of reduced need
for transportation infrastructure, chemical additives and preservatives, and
refrigeration.
The impacts during the production phase also vary between types of foods,
which can also result in underestimates of the impacts. Production of meats,
especially red meats, requires large amounts of land to generate the crops
needed for animal feed. Because not all energy is passed from feed to the
animal, using meats for our food is inefficient from an energy perspective.
It takes over 8 pounds of grain to feed a cow enough to generate 1 pound of
weight gain. That grain must be grown on land that can long longer produce
food directly for human consumption. The amount of land required to
produce animal feed is known as ghost acres. Ghost acres also extend to
the areas required to provide the fuel, water, and other resources needed for
animal feed, and for the overall support of animals[footnote]. While some
other meats such as pork, poultry, and especially fish, use proportionally
less feed, there are other concerns about the environmental impacts of diets
with large amounts of meat.
In other environmental contexts, ghost acres refer more broadly to all land
areas being used indirectly to support human activity and areas not usable
due to other human influences
farms, have become the primary source of livestock for meat in the U.S.,
Europe, and many other countries. The technological innovations employed
in these operations have increased the speed and volume of meat
production, but have raised health concerns. Antibiotics and hormones used
increasingly on animals in CAFOs may be passed on to humans during
consumption, even though there is currently no way of knowing a safe level
of those substances in our diets. The overuse of antibiotics in CAFOs also
results in antibiotic-resistant pathogens. In addition to the impacts from the
ghost acres, there are other ecological impacts such as pollution from
massive amounts of concentrated manure. Although the distance meat is
transported has an environmental impact, the other concerns are more
significant.
Confined Animal Feeding Operations (CAFOs)This image shows a
CAFO for cattle. CAFOs have raised health concerns for human
consumption of the meat produced in them. Source:
eutrophication&hypoxia
Implementation
The ongoing investigations of food miles have affected businesses, groups,
and individuals in various ways. As mentioned above, paying closer
attention to the distance food travels can be a good business strategy
because fuel costs money. Centralization of processing and distribution
centers in the United States has resulted in a relative frequent occurrence of
shipping produce thousands of miles only to end up in supermarkets back
near its origin. In many cases the initial savings from building fewer
centralized facilities is exceeded in the long-term by the continual shipping
costs. As a result, some retailers are encouraging outside scrutiny of their
habits, because it can result in increased profits. At the other extreme, the
rise in food miles in some cases is driven entirely by money. Fish caught
offshore Norway and the United Kingdom, for example, is sent to China for
cheaper processing before being returned to European markets.
An awareness of the impact of food miles has led to many groups
advocating local foods. Local farmers' markets have appeared and expanded
around the United States and elsewhere, providing increased access to fresh
foods. Community-supported agriculture programs create share-holders
out of consumers, making them more personally invested in the success of
local economies, while farmers gain some financial security. Campaigns by
community groups are influencing retailers and restaurants by scrutinizing
the food-purchasing decisions. The reciprocal is also true as retailers and
restaurants advertise their sustainability efforts. See Resources for examples
of local farmers' markets in Illinois.
Illinois Farmer's Market Colorful produce at an Illinois farmer's
market. Source: Maycomb Paynes
Yet, there are challenges to the implementation of food miles as a concept.
Suppliers, such as individual farmers, might opt for the reliable annual
purchase from a mass-distributor. Consumers might make decisions solely
on the sticker price, not knowing the other impacts, or consumers might
know the impacts but choose the immediate economic incentive. Some of
these challenges can be addressed by education. This can include efforts
such as eco-labeling — labels, often by third parties, that independently
attest to the environmental claims of products. This can influence some
consumers, but larger buyers like school systems and restaurant chains may
require other incentives to change purchasing practices. The source of these
incentives, or alternatively, regulations, might come from government
agencies, especially those with desires to support local economies.
However, there is no consensus regarding who should be evaluating and
monitoring food miles.
Summary
The criticisms of food miles are valid, and work is continually being done
incorporate the many factors that more completely show the environmental
impacts of transporting food. This can be a time consuming process, and the
many variables are usually not readily available to consumers. A frozen
pizza might contain many types of ingredients from various areas that are
transported to individual processing plants before being assembled in
another location and forwarded to distribution centers before being shipped
to stores. Even if this process is eventually simplified, eating decisions
should not be made solely on the basis of food miles, which cannot account
for the variations in transportation and production methods or the social and
economic impacts.
This does not mean that food miles are never a useful tool. When
comparing similar products (e.g., onions to onions) with other similar
externalities (e.g., production and transportation methods), food miles
provide a convenient way for consumers to begin to make informed
decisions about their purchases. Even though food transportation is a
relatively small portion of the overall impact of our food consumption,
changes to any phase of the process can have a positive additive effect and
make a real contribution to environmental health. Moreover, most of the
benefits for using food miles can likewise apply to many of our non-food
purchases, with allowances for some of the same drawbacks. Additionally,
the discussion could be expanded to include other kinds of decisions, such
as where to live in relation to location of job, and where to take a vacation.
In general, the concept of food miles reflects the need to understand how
hidden influences generate environmental, social, and economic impacts.
Review Questions
Exercise:
Problem:
What are some of the problems with comparing food miles for a
cheeseburger to those for a vegetarian salad?
Exercise:
Problem:
Why might food producers in isolated but prosperous areas (like
Hawaii or New Zealand) argue against the use of food miles?
Exercise:
Problem:
Do you think increased reliance on food miles is good or bad for rural
areas in developing countries? Explain your decision.
References
Cleveland, D. A., Radka, C. N., Miiller, N. M., Watson, T. D., Rekstein, N.
J., Wright, H. V. M., et al. (2011). Effect of localizing fruit and vegetable
consumption on greenhouse gas emissions and nutrition, Santa Barbara
County. Environmental Science & Technology, 45,4555-4562. doi:
10.1021/es1040317
Saunders, C., Barber, A., & Taylor, G. (2006). Food miles — comparative
energy/emissions performance of New Zealand's Agriculture Industry.
Lincoln University Agribusiness & Economics Research Unit Research
Report, 285, 1-105.
Weber, C. L., & Matthews, H. S. (2008). Food-miles and the relative
climate impacts of food choices in the United States. Environmental
Science & Technology, 42, 3508-3513. doi: 10.1021/es702969f
Resources for locating farmers' markets in Illinois:
¢ Local Harvest http://www.localharvest.org
e Illinois Stewardship Alliance http://www.ilstewards.org
e Slow Food Chicago http://www.slowfoodchicago.org
e Illinois Farmers Markets, Illinois Department of Agriculture
http://www.agr.state.il.us/markets/farmers/
Glossary
community-supported agriculture
A collaborative system where local food producers and consumers
share in the costs and harvests associated with farming.
confined (or concentrated) animal feeding operation (CAFO)
The practice of raising livestock in high-density settings to maximize
production speed; some of the largest CAFOs have more than 100,000
cattle, 10,000 hogs, or 1,000,000 chickens at a single facility;
sometimes called factory farming.
food miles
The distance food travels from producer to consumer.
food security
The measure of the availability and access to sufficient, safe, and
nutritious food.
ghost acres
The acres of land needed to indirectly support human needs, or land
that is unavailable because of habitat degradation.
locavore
A person who consumes locally-produced food products.
Environmental Performance Indicators
In the module, you will learn about the data included in creating an
environmental performance indicator, the strengths and weaknesses of the
environmental sustainability index and emergy performance index and the
differences between some of the major environmental performance
indicators.
Learning Objectives
After reading this module, students should be able to
¢ understand the data included in creating an environmental performance
indicator
e be able to state some general strengths and weaknesses of the
environmental sustainability index and emergy performance index
e know the differences between some of the major environmental
performance indicators
Introduction
Because there are so many types of environmental problems, there are
many projects designed to address these concerns and likewise many
methods to assess them. Collectively, the methods for assessing
environmental impactsand the uses of natural resources (both living and
non-living) are called environmental performance indicators. Generally,
performance indicators are used in fields ranging from marketing and
economics to education and legal studies to measure a project's progress
and/or success. Some indicators can evaluate the actions of a single
individual, while others are broad enough to reflect the efforts of entire
nations or even the globe. Specifically, environmental performance
indicators (EPIs) examine environmental issues such as pollution,
biodiversity, climate, energy, erosion, ecosystem services, environmental
education, and many others. Without these EPIs, the success or failure of
even the most well-intentioned actions can remain hidden.
Because of the diversity of observational scales and topics, not all EPIs are
useful in all scenarios. However, all EPIs should indicate whether the state
of the environment is changed positively or negatively, and they should
provide a measure of that change. An EPI is also more meaningful if it can
quantify the results to facilitate comparison between different types of
activities. But before an EPI is selected, targets and baselines must be
clearly articulated. Vague targets are difficult to evaluate, and the results
may be uninformative. The EPI selected must use indicators that are
definitively linked to the targets, are reliable and repeatable, and can be
generated in a cost and time efficient manner.
To evaluate an activity, an EPI needs to include information from up to four
natural resources or ecosystem services being used. Outputs are the goods
or services that result from that activity. While outputs can often be
quantified, outcomes typically cannot be and instead represent
environmental, social, and economic dimensions of well-being. In some
cases it is useful to think of outcomes as why an output was sought;
however, outcomes can also be unanticipated or unwanted effects of an
output. Impacts refer to the longer-term and more extensive results of the
outcomes and outputs, and can include the interaction of the latter two
indicators.
For example, coal can be an input for an electricity-generating plant
because we need the output (electricity) to turn on lights in our homes. Two
outcomes would include the ability to read at night because of the
electricity and the visible air pollution from the power plant smoke stacks.
An impact of being able to read more can be a better-educated person, while
an impact of the greenhouse gas emissions from burning coal is increased
potential for global climate change. This is a simplistic example which does
not include the majority of relevant indicators (inputs, outputs, outcomes,
and impacts) for a complete and more meaningful analysis.
We can then evaluate each of the indicators. Is the input (coal) an
appropriate choice? Is there enough for the practice of burning it to
continue? Are there problems, such as political instability that could
interrupt continued access? Does the output (electricity) sufficiently address
the problem (in this case, energy for turning on lights)? Is the output
produced and delivered in a timely manner? Is it provided to the appropriate
consumers and in a quantity that is large enough? Does the output create the
desired outcome (being able to read at night)? Does it also result in
unwanted outcomes (air pollution)? Do the outcomes result in long-term
impacts (such as life-long learning or decade-long climate change) that are
widespread?
Note that outcomes and impacts can be either positive or negative. The
strength of an EPI lies in its ability to look at the bigger picture and include
multiple variables — particularly with regard to the impacts. However,
whether an impact is considered meaningful depends on the values and
perspectives of the individuals and groups involved. Judgment plays a role
because of the difficulty in comparing completely different impacts. How
do you compare life-long learning and climate change in the above example
about the use of coal?
Uses
Monitoring the impacts of both short-term and long-term activities with
EPIs allows decision makers to make changes that result in performance
with lesser environmental impacts. In some cases, changes can be made to
ongoing projects, or the results of an EPI can be used for publicity if the
performance data indicate the activity is environmentally-sound. In other
cases, the EPI establishes a performance benchmark against which other
projects are measured, or the results are used in the strategic planning phase
while projects are in development. In this way, past successes and failures
can both be incorporated into future plans.
Use of EPIs requires production of multiple data points. A single
application of an EPI does not mean much until placed into a larger context.
For example, an EPI might evaluate the impact of your city's recycling
efforts (see Figure Municipal Solid Waste Recycling Rates), but that
result can be difficult to interpret without additional data that can be
presented in multiple ways:
e Absolute values: Is the impact greater or less than that of other cities?
How does the total cost of the recycling program compare?
e Normalized values: How does the per person impact compare to
another city, country, business, etc.? What is the amount of aluminum
recycled per dollar spent on recycling?
e Trends: Is your city improving, or is the progress your city sees in
recycling better than that that of other cities? This could be asked of
either absolute or normalized data: Is the total amount of aluminum
recycled in your city increasing? Is the per-person amount of
aluminum recycled in your city increasing?
MSW Recycling Rates
1960 to 2007
90.0 85.0980.0%
40.0%
30.0%
A Total MSW recycling (million tons)
Percent of generation recycled
; 00.0%
1960 1985 1970 1975 1980 1985 1990 1995 2000 2005 2007
——*— Total MSW Recycling eqjee Percent Recycling
Municipal Solid Waste Recycling Rates Municipal solid waste
recycling rates in the United States from 1960-2007. Source: EPA
Major EPI Areas
Most EPIs focus on one or a few categories of environmental problems and
do not attempt to be all-inclusive methods of evaluating sustainability. A
few of the more common categories are briefly described below.
Biodiversity is the number and variety of forms of life, and can be
calculated for a particular tree, an ecosystem, a nation, or even the planet.
Food, fuel, recreation, and other ecosystem services are dependent on
maintaining biodiversity. However, biodiversity is threatened by overuse
and habitat destruction (see Figure Endangered Animals). Because the
actual number of species alive is not known, biodiversity indicators often
use proxy data. These include patterns of habitat preservation and resource
use, because they are the primary factors influencing biodiversity. The
better-known groups of organisms, such as birds and mammals, are also
monitored for a direct count of biodiversity, but vertebrates are a tiny
proportion of life and cannot accurately reflect changes in all species.
Number of globally threatened mammal species in each country in 2000
between 64 to 140
between 28 to 63
between 13 to 27
|_| between 0 to 12
Endangered Animals I|lustration shows the number of endangered
animals in each country of the world. Source: World Atlas of
Biodiversity
Wood is harvested for timber and fuel, but forests are also cleared for
agricultural fields and housing developments. Such deforestation frequently
leads to rapid soil erosion and extinctions. Cutting of forests also results in
changes to the water cycle, altering precipitation patterns and rates, and
nutrient cycles, such as the release of carbon dioxide into the atmosphere.
At the same time as deforestation takes its toll in places, trees are being
planted elsewhere. Developed countries are increasing their forested areas,
but this is commonly being done at the expense of developing countries,
which are exporting their wood (see Figure Deforestation at the
Haiti/Dominican Republic Border). Forestry indicators in EPIs include
the annual change in forested areas, but can be broken down into the types
of forests because each has different environmental impacts. Another
indicator is the use of non-sustainable wood resources. Tree farms and some
harvesting methods provide renewable supplies of wood, while clear-
cutting tropical forests does not. Irresponsible wood harvesting produces
negative results for ecosystem health.
Deforestation at the Haiti/Dominican Republic
Border Satellite photograph show deforestation of
Haiti (on the left) at the border with the Dominican
Republic (on the right). Deforestation on the Haitian
side of the border is much more severe. Source:
NASA
Air, water, and land pollution directly, and adversely, impacts human and
ecosystem health. It also has economic consequences from the damage of
natural resources and human structures. In many cases the level of
pollutants can be measured either in the environment or at the point of
emissions. Additional indicators include whether pollution monitoring even
occurs, to what extent legal maximum levels are enforced, and whether
regulations are in place to clean up the damage. Visit the EPA's
MyEnvironment application to learn more about environmental issues in
your area.
Greenhouse gas emissions and ozone depletion are results of air pollution,
but are frequently placed in a separate category because they have global
impacts regardless of the source of the problem. Levels of greenhouse gases
and ozone-depleting substances in the atmosphere can be measured directly,
or their impacts can be measured by looking at temperature change and the
size of the ozone hole. However, those methods are rarely part of EPIs
because they do not assign a particular source. Instead, EPIs include the
actual emissions by a particular process or area.
Examples of EPIs
There are dozens of EPIs that can be used to evaluate sustainability. Below
are two examples of multi-component methods that allow comparisons at a
national level, which is necessary for promoting many types of systemic
change.
Environmental Sustainability Index
The environmental sustainability index (ESI) was created as a joint effort
of Yale and Columbia universities in order to have a way to compare the
sustainability efforts and abilities of countries. Visit the ESI website for
more information such as maps and data. First presented in 2000 at the
World Economic Forum, the ESI has quickly gained popularity because it
aids decision-making by providing clear comparisons of environmental
statistics. The basic assumption of the ESI is that sustainable development,
the use of resources in a way to meet societal, economic, and environmental
demands for the long-term, requires a multi-faceted approach. Specifically,
the ESI uses 76 variables to create 21 indicators of sustainability.
The indicators cover five categories, with each description below indicating
the condition that is more sustainable:
¢ environmental systems — maintaining and improving ecosystem health
e reducing environmental stress — reducing anthropogenic stress on the
environment
e reducing human vulnerability — having fewer negative impacts on
people from the environment
¢ capacity to respond to environmental challenges — fostering social
infrastructures that establish ability and desire to respond effectively to
environmental challenges
¢ global stewardship efforts — cooperating with other countries to
address environmental problems.
The ESI scores range from 0, least sustainable, to 100, most sustainable,
and is an equally-weighted average of the 21 individual indicators. The
highest-ranked countries in 2005 (Finland, Norway, Uruguay, Sweden, and
Iceland) all had in common abundant natural resources and low human-
population densities. At the other extreme, the lowest-ranked countries
(North Korea, Iraq, Taiwan, Turkmenistan, and Uzbekistan) had fewer
natural resources, particularly when compared per capita, and have made
policy decisions often against their own long-term best interests. However,
it is important to note that most countries do not excel, or fail, with regard
to all 21 indicators; every nation has room for improvement. Each country
will also have its own environmental priorities, attitudes, opportunities, and
challenges. For example, the United States scores high in the capacity to
respond to environmental challenges, but low in actually reducing
environmental stress.
ESI scores have sparked some healthy competition between nations; no one
wants to be seen as underperforming compared to their peers. After the pilot
ESI rankings in 2000 and the first full ESI rankings in 2002, Belgium,
Mexico, the Philippines, South Korea, and the United Arab Emirates, all
initiated major internal reviews that resulted in the initiation of efforts to
improve environmental sustainability. Because ESI data are presented not
only as an overall average but also as 21 independent indicators, countries
can focus their efforts where most improvement could be made. Countries
dissatisfied with their rankings have also begun to make more of their
environmental data accessible. Initial rankings by ESI score had missing or
estimated data in many cases, but by making more data available, more
accurate overall assessments are possible. For example, the Global
Environmental Monitoring System Water Program, an important source of
water quality information, had data contributions increase from less than 40
countries to over 100 as a result of the ESI.
Several similar ranking methodologies have emerged from the ESI. They
vary in the number and type of variables included and indicators produced.
Some also calculate an overall average by weighting some indicators more
than others. However, they all share the same 0-100 scale and have
individual indicators that allow targeted improvement of the overall scores.
Emergy Performance Index
One drawback of the ESI is that the indicators measure items as different as
percentage of endangered animals, recycling rates, government corruption,
and child mortality rates. The scope of the variables has been criticized
because they may not be comparable in importance, and many others could
be added. The term, emergy, is a contraction of EMbodied enERGY. The
variables, and instead creates a single unit that can be used to describe the
production and use of any natural or anthropogenic resource.
The first step of calculating EMPI is to inventory all material and energy
inputs and outputs for all processes and services. Every process and service
is then converted to its equivalent in emergy. The amounts of emergy of
each type are summed. There are several possible ways to group emergy by
type and to combine the data, but generally the goal is to create either a
measure of emergy renewability (as an indicator of stress on the
environment) or emergy sustainability (which combines renewability with
the total productivity and consumption or emergy).
Calculating the emergy equivalents of materials and energy can be done
easily with a conversion table, but creating the table can be a challenge.
Burning coal releases an amount of energy that is easy to measure and easy
to convert to emergy. However, determining the amount of energy required
to create coal is nearly impossible. Similarly, how can you quantify the
emergy conversion factor for objects like aluminum or for ecosystem
services like rainfall? It is difficult, but possible, to place a dollar value on
those objects and services, but assigning an energy equivalent is even more
tenuous. While converting everything to a common unit, emergy, simplifies
comparisons of diverse activities and processes like soil erosion and
tourism, there are concerns about the accuracy of those conversions.
Comparisons
There are no perfect measures of sustainability, and different indicators can
sometimes give conflicting results. In particular this happens when
perspectives on the most important components of sustainability, and the
methods to address them, differ. Therefore, it is often useful to examine the
main characteristics of several Environmental Performance Indicators to
find the one most appropriate for a particular study. As an example, ESIs,
EMPIs, and ecological footprinting (discussed in a previous section) are
compared below.
Ecological footprinting (EF) has units that are the easiest to understand —
area of land. Both EF and EMPI employ only a single type of unit, allowing
for use of absolute variables and permitting quantitative comparisons.
However, EF does not use multiple indicators to allow for focused attention
on impacts. EMPI can also be used as scaled values (such as the proportion
of emergy from renewable sources), in the same manner as ESI. However,
ESI combines multiple units of measurements, which can provide a more
holistic perspective, but at the same time leads to concerns about combining
those data.
Of the three, ESI and EMPI take into account wastefulness and recycling,
and only ESI includes the effects of all emissions. But while ESI includes
the most variables, it is the most complex to calculate; the simplest to
calculate is EF.
Because ESI includes social and economic indicators, it can only compare
nations (or in some cases, states or other levels of governments). EF and
EMPI are effective at comparing countries, but can also be used at scales
from global down to individual products.
All three of the EPIs compared here can be useful, but each has their
limitations. Additionally, there are scenarios where none of these are useful.
Specific environmental education projects, for example, would require
different types of performance indicators.
Review Questions
Exercise:
Problem: What is the difference between energy and emergy?
Exercise:
Problem:
In what way(s) is ESI a better method of assessing sustainability than
EF and EMPI?
Exercise:
Problem:
The ESI creates indicators in five areas. In which of the areas do you
think the indicators are the least reliable?
Exercise:
Problem: Why do EPIs require multiple data points to be useful?
Additional Resources
Environmental Sustainability Index
(http://sedac.ciesin.columbia.edu/es/esi/)
Glossary
emergy (EMbodied energy)
The unit of energy into which any resource, product, or process can be
converted to simplify comparisons between diverse items.
emergy performance index (EMPI)
Value produced by converting all materials and processes to amounts
of energy in order to evaluate renewability and sustainability.
environmental sustainability index (ESI)
A composite value produced by including ecological, social,
economic, and policy data.
environmental performance indicators (EPI)
Any of the ways in which environmental outcomes and/or impacts can
be assessed.
impacts
Long-term and more widespread results of an activity.
inputs
The specific resources or services used by an activity.
outcomes
The short-term results of an activity.
outputs
The goods and services being created by an activity, and the manner
and degree in which they are delivered.
Case Study: UN Millennium Development Goals Indicator
In 2000 the United Nations created the Millennium Development Goals
(MDGs) to monitor and improve human conditions by the year 2015.
In 2000 the United Nations created the Millennium Development Goals
(MDGs) to monitor and improve human conditions by the year 2015. This
framework was endorsed by all UN member nations and includes goals in
eight areas: hunger/poverty, universal primary education, gender equity,
infant mortality, maternal health, disease, global partnerships, and
environmental sustainability.
Each of the MDGs on basic human rights has one or more targets, with each
target having specific indicators for assessment. Most of the targets have a
baseline year of 1990 and specify an achievement rate. For example, one
target is to halve the proportion of people suffering from hunger. By
specifying a proportion, targets can be monitored separately at national,
regional, and global levels. Visit the interactive map at MDGMonitor to
track and monitor progress of the Millennium Development Goals.
The underlying principle of the MDGs is that the world has sufficient
knowledge and resources to implement sustainable practices to improve the
life of everyone. Annual progress reports suggest that this principle may be
realistic only for some targets. The targets within environmental
sustainability are the implementation of national policies of sustainable
development, increased access to safe drinking water, and improvements to
urban housing. There are success stories: efforts to increase availability of
clean water have resulted in improvements faster than expected. However,
not all indicators are showing improvement. Impacts of climate change are
accelerating, and risks of physical and economic harm from natural
disasters are increasing. Moreover, these impacts and risks are concentrated
in poorer countries — those least able to handle the threats. Overall, results
are mixed.
The worldwide rate of deforestation is still high but has slowed. Large-scale
efforts to plant trees in China, India, and Viet Nam have resulted in
combined annual increases of about 4 million hectares of forests since
2000. Unfortunately, that is about the same rate of forest loss in South
America and Africa each. Globally, the net loss of forest from 2000 to 2010
was 5.2 million hectares per year, down by a third from the 1990s.
The world will likely meet the target of halving the proportion of people
without access to clean water, with the majority of progress made in rural
areas. By 2008 most regions exceeded or nearly met the target levels. The
exceptions were Oceania and sub-Saharan Africa, which had only 50% and
60% respectively of their populations with access to improved water
sources. Those regions will almost certainly miss the target. They, and most
other developing regions, will also miss the target of halving the proportion
of the population lacking improved sanitation facilities. In fact, the total
number of people without such access is expected to grow until at least
2015:
From 1990 to 2007, emissions of carbon dioxide rose in developed regions
by 11%; in developing regions, which have much higher rates of population
growth, emissions increased by 110%. While most indicators have shown
either progress or minimal additional harm, carbon dioxide emissions stand
out as one of the significant failures in achieving global sustainability.
Efforts to preserve biodiversity have made only minimal progress. One
target was to have 10% of each of the world's terrestrial ecosystem types
protected by 2010; only half were. The proportion of key biodiversity areas
protected stagnated in the 2000s, after showing faster improvements in the
1970s-1990s. As a result, the number of birds and mammals expected to go
extinct in the near future has increased.
The environmental sustainability target for urban housing was meant to
significantly improve the lives of 100 million slum-dwellers by 2020. This
target differed from most others not only by using a later date of 2020, but
by lacking a specified proportion of the population. Setting a target as an
absolute value for the entire globe obscures the progress in individual
countries, so this criterion may be revisited. From 1990 to 2010, the
proportion of slum-dwellers decreased from 46% to 33%. However, during
the same time, the number of people living in slums increased from 657
million to 828 million. Over 200 million slum-dwellers achieved access to
clean water and improved sanitation facilities, so the target was met.
However, it is widely acknowledged that the target was set too low.
Even as we continue to strive toward the MDGs 2015 target date, it is also
necessary to think beyond them. Changing demographics will drive shifts in
the global economy and the use of resources. Increased effects of climate
change will result in greater volatility, while technological developments
can open new opportunities. In light of these changes, evaluation of the
MDGs must assess their utility after 2015. Should the general framework
stay in place, should it be modified with new approaches, or should it be
replaced with something fundamentally different?
Sustainability and Business
In this module, the following topics are presented: 1) the incorporation of
sustainability into businesses plans, 2) sustainable product chains, and 3)
measuring and assessing sustainable performance.
Learning Objectives
After reading this module, students should be able to
e understand how businesses incorporate sustainability into their plans,
the basis of sustainable product chains, and factors that need to be
considered in measuring and assessing sustainable performance
Introduction
Throughout this text the integrative nature of environmental, social, and
economic sustainability has been stressed. In this chapter, various ways of
framing the sustainability paradigm and measuring progress toward its
achievement have been presented. This section focuses more directly on
businesses, and how they attempt to incorporate sustainability into their
decisions and plans. The business sector, continually seeking ways to create
competitive advantages, has become acutely aware of the general value of
adjusting various business models to accommodate consumers’ desires for
sustainable products and services. Still, the broad definition of sustainable
development provided by the Brundtland report is a difficult one to make
operational. The World Business Council for Sustainable Development has
adapted Brundtland to a view more understandable to business interests,
focusing on living within the “interest” of natural systems and being
cautious about drawing down the “principal” (i.e. degrading natural
ecosystems), but there remain substantial differences on precisely how to
measure progress toward the goals of the sustainability paradigm.
It is a common practice for businesses to refer to the triple bottom line, a
reference to the value of a business going beyond dollar profitability to
include social and environmental costs and benefits as well. Indeed, many
of the tools and indices outlined in Module Life Cycle Assessment and
Module Sustainability Metrics and Rating Systems are widely used by
businesses to measure progress toward corporate goals. However, there is
no agreed upon way of using these tools, and many businesses have
developed their own methods for assessing progress. This has, inevitably
perhaps, led to claims and counter-claims by various parties about the
“sustainability” of their products or services. Such claims usually find their
way into corporate brochures and advertising so that, often without
substantive backing or very subjective analysis, the impression of
significant corporate sustainability is created, practices known generally as
greenwashing. Greenwashing is a concern because these kinds of
advertising messages can mislead consumers about the “the environmental
practices of a company or the environmental benefits of a product or
service” (Greenpeace, 2011). Nevertheless, businesses must ultimately
generate profits to remain viable, and increasingly they are being held to
account for their impacts on all aspects of business operations, however
difficult it may be to assign value to decisions made under conditions of
considerable uncertainty. The intergenerational mandate of Brundtland and
the nature of modem environmental problems facing society ask that
business plans extend far beyond the usual five to ten year range.
Tools for Assessing Sustainability in Business
One useful organizational framework for envisioning different kinds of
costs and benefits that businesses encounter is referred to as Total Cost
Assessment (TCA). TCA assigns levels of uncertainty to the types of costs
associated with various aspects of business activities. Typically five such
types are recognized:
¢ Type I (Direct Costs) — Costs associated with direct operation of the
manufacturing or service enterprise that can be readily attributed to a
specific activity. Labor, medical, materials, land, and energy are
examples of this type of cost.
e Type II (Indirect Costs) — Costs similar to Type I that are not easily
assigned to a specific activity and thus are born more generally by the
company. These include various kinds of overhead costs, outsourced
services and subcontracts (e.g. component subassemblies, janitorial
needs), and general support activities such as central offices for
purchasing, human resources, etc.
e Type II (Contingent Liability Costs) — These are costs associated with
environmental cleanup, non-compliance fines, product or service
liability, civil suits, and accidents.
e Type IV (Internal Intangible Costs/Benefits) — These are costs and
benefits that accrue to a business that are connected to a variety of
intangibles such as worker morale, consumer loyalty, corporate image,
and branding of products and services.
e Type V (External Costs) — Put simply, Type V costs are those
associated with environmental degradation. They are “external” in the
sense that normal financial accounting does not include them; the
damage is born in a general sense by society at large. Environmental
protection requirements that are enforceable by various laws (see
section Government and Laws on the Environment), and mandated
market or taxation mechanisms, are policy decisions meant to
internalize these costs, forcing the generator of the pollution to either
pay for the damage or prevent damage in the first place.
Taken as a whole, these cost/benefit types include all three of the basic
elements of the sustainability paradigm. However Type IV and V costs are
often difficult to assign a dollar value to; indeed even if this can be done,
projecting their value into the future is an uncertain science.
Life cycle assessment (LCA) can also be used to visualize and organize a
sustainability model for businesses (See Module Life Cycle Assessment for
more information). Recall that LCA grew out of industry’s needs to
understand how product manufacturing systems behave, and to develop
workable models that could be used to control and optimize material and
energy flows, ensure product quality, manage environmental impacts, and
minimize costs (these functions are collectively referred to as the supply
chain). An expanded use of LCA incorporates the complete product chain,
examining consumer uses, benefits and costs, and the post-consumer
disposition of the product. This has led to product conceptualization and
development, and in some cases regulatory reform, that incorporate
business practices and plans built upon the concept of eco-efficiency, and
evolutionary business model in which more goods and services are created
with less use of resources, and fewer emissions of waste and pollution.
Extended product/producer responsibility involves the creation of financial
incentives, and legal disincentives, to encourage manufacturers to make
more environmentally friendly products that incorporate end-of-life costs
into product design and business plans. For example one business model
that is conducive to EPR is a “lease-and-take-back” model in which
products must eventually come back to the manufacturer or retailer, who
then must reckon with the best way to minimize end-of-life costs.
Remanufacturing, recycling, and reuse of materials are the intended results
of EPR, but ordinary disposal, including landfilling or incineration, can also
be an option.
Figure LCA Framework Applied to Product Development, illustrates in
a general way how the LCA framework can be structured for understanding
how product development can benefit from the various material and
information transfers and feedback loops along the product chain. Such a
figure illustrates the complexities involved in creating, marketing, and
discerning the impacts of a product or service, and raises the general
concept of what is often referred to as product stewardship, an approach
in which products are conceived, designed, manufactured, and marketed
within a systems thinking context. It is a way of framing environmental
problems that recognizes the three parts of the sustainability paradigm, and
incorporates the concepts of sustainable manufacturing, marketing, utility-
to-society, impacts of the use of the product, and end-of-life disposition of
the product.
Manufacturing, Consumer uses
fabrication, and and utility
assembly
Environmental End-oFlife
Impacts disposition
Policy
guidelines
LCA Framework Applied to Product Development. Generalized
view of the life cycle product chain, showing major material and
information transfers and feedback loops. Source: Tom Theis
Creating Uniformity
The problem of lack of uniformity in measuring, assessing, and valuing
business actions taken at least in part for the sake of sustainability might be
dealt with more effectively through the development of uniform standards
and metrics that are applied by an agreed upon authority who uses
transparent methodologies and reporting techniques so that other
companies, and consumers, can make more objective judgments about
comparative performances. From what has been presented in this section
this may appear to be a near-impossible task. Yet attempts in this direction
are being made, for example by the aforementioned World Business
Council for Sustainable Development, the Organization for Economic
Cooperation and Development, and the United Nations Millennium
Development Goals. One of the more popular approaches for measuring
and ranking corporate sustainability has been developed by the Dow Jones
Corporation (DJC), through its Sustainability Index (DJSI). It may seem
ironic that such a bastion of the free market economy has put together a
system for measuring and assessing corporate sustainability, yet the size and
general acceptability of DJC by corporations and investors work in favor of
the establishment of an objective and transparent index. The DJSI itself was
created in 1999 in response to the need, articulated from many sectors
including consumers, for a way to assess progress toward sustainable
corporate responsibility. The index contains three general evaluative sectors
— economic, social, and environmental — that reflect the Brundtland
definition. Each sector is composed, in turn, of specific categories as
follows:
Economic
e Codes of Conduct/Compliance/Corruption and Bribery
e Corporate Governance
e Risk and Crisis Management
e Industry-specific Criteria
Social
e Corporate Citizenship and Philanthropy
e Labor Practice Indicators
e Human Capital Development
e Social Reporting
e Talent Attraction and Retention
¢ Industry-specific Criteria
Environmental
e Environmental Performance (Eco-efficiency)
e Environmental Reporting
e Industry-specific Criteria
Each of these categories is composed of quantitative measures and assigned
a specific, and constant, weighting. From the data gathered, a “best-in-
class” (i.e. industry class) ranking is published annually. The index has
engendered considerable corporate competition such that mere attainment
of the previous year’s statistics, for a given company, usually results in a
drop in rank. Of course one can argue with the choice of categories, or the
data that are gathered and the way categories are parameterized, or with the
weighting scheme used, but the important aspects of DJSI (and other
sustainability rankings) is its comprehensiveness, uniformity, and
transparency.
Summary
In the final analysis, no economy can move in the direction of sustainability
without the active participation of the business sector. In other words,
significant progress cannot be achieved through government or individual
actions alone. As noted above, this creates difficulties and conflicts for
businesses. As they continue to work together in the future, businesses and
sustainability experts face many questions such as: What are the best
measures of sustainability and how should businesses develop and plan for
delivering more sustainable products and services? Is reliance on eco-
efficiency enough to reduce the impacts of increasing consumption? Should
businesses play a more significant role in educating consumers on the
factors that affect sustainable development? How can businesses adapt to
uncertainties that lie beyond the near term? What is the role of government
in overseeing or regulating business activities that contribute to
sustainability?
Review Questions
Exercise:
Problem:
Find a product chain for the manufacture of a major consumer item
such as a flat screen television, a computer, or an automobile and cast
the stages of the chain in life cycle form as shown in Figure LCA
Framework Applied to Product Development. As part of your
answer, define the various information transfers and feedback loops
involved.
Exercise:
Problem:
Consider the various types of costs in the total cost accounting
framework. In proceeding from Type I to Type V, give reasons why
uncertainties usually increase at each level?
Exercise:
Problem:
What are the main attributes of a sound index for measuring progress
toward sustainability of products and services?
Resources
The World Business Council for Sustainable Development
References
Greenpeace (2011). Greenwashing. Greenpeace. Retrieved December 17,
2011 from http://stopgreenwash.org/
Glossary
eco-efficiency
An evolutionary business model in which more goods and services are
created with less use of resources, and fewer emissions of waste and
pollution.
end-of-life costs
Those costs that arise through activities associated with the disposition
of a product at the end of its useful life. These include costs associated
with disposal, recycling, reuse, and remanufacturing.
extended product/producer responsibility
The creation of financial incentives, and legal disincentives, to
encourage manufacturers to make more environmentally friendly
products that incorporate end-of-life costs into product design and
business plans.
greenwashing
Claims made by businesses about the superior contributions of their
products and services to sustainability without substantive backing or
via a very subjective analysis.
product chain
Those stages in the conception, design, manufacture, marketing, use,
and end-of-life that define the impacts of a product or service on
society.
product stewardship
An approach to product development in which products are conceived,
designed, manufactured, and marketed within a “systems thinking”
context. It is a way of framing environmental problems that recognizes
the three parts of the sustainability paradigm, and incorporates the
concepts of sustainable manufacturing, marketing, utility-to-society,
impacts of the use of the product, and end-of-life disposition of the
product.
systems thinking
In the context of sustainability, systems thinking is a way of
conceiving human-created and natural systems as functional parts of a
larger, integrated system.
triple bottom line
A reference to the value of a business going beyond dollar profitability
to include social and environmental costs and benefits as well.
The Human Dimensions of Sustainability: History, Culture, Ethics
This module introduces the chapter "The Human Dimensions of
Sustainability: History, Culture, Ethics" in "Sustainability: A
Comprehensive Foundation"
Source: Earth Day Network
Once we begin talking about sustainability, it’s hard to stop. That’s because
sustainability is truly the science of everything, from technical strategies for
repowering our homes and cars, to the ecological study of biodiversity in
forests and oceans, to how we think and act as human beings. This latter
category—the “human dimensions” of sustainability—is the focus of this
chapter. Much sustainability discourse focuses on scientific, technical and
regulatory issues, but there is increasing awareness that without changes in
people’s attitudes and patterns of behavior, and how these attitudes are
reflected in public policymaking priorities, meaningful reform toward a
more sustainable management of natural resources will be impossible. One
key to this problem is that we are accustomed to thinking of the
environment as a remote issue. Even the words “environment” and “nature”
themselves suggest the habitual view we take of ourselves as somehow
independent of or superior to the planet’s material resources and processes.
The truth is different. Humanity is but a thread of nature’s web, albeit an
original and brilliant thread. So brilliant indeed that we are now shaping the
evolution of the web itself, to our short-term advantage, but in ways that
cannot be sustained.
One example of the centrality of the human dimensions component of
sustainability studies is the fact that sustainable technologies of food and
energy production are increasingly available, but have yet to be adapted on
the necessary scale to make a difference to humanity’s overall
environmental footprint on the planet. Many look to technology for answers
to our myriad environmental problems, but the fact that even the limited
technological innovations that exist lack support and have been
inadequately deployed is a complex human issue, touching an essential
resistance to change in our economic and political structures, our lifestyles
and culture and, at the micro-level, basic human psychology and behavior.
This chapter will explore these human dimensions of the sustainability
challenge, with an emphasis on the historical and cultural factors that have
placed us on our dangerously unsustainable path, and which make changing
course so challenging.
Sustainability in human terms is, first and foremost, a commonsense goal:
to ensure that conditions on earth continue to support the project of human
civilization, that widely diverse populations of the global community not
slip into protracted crisis on account of deteriorating environmental
conditions and depleted resources. This preventive dimension of
sustainability discourse inevitably involves doom projections. Despite the
popularity of apocalyptic, end-of-the-world scenarios in Hollywood movies,
science fiction, and some corners of the blogosphere, the biological end of
the human race remains scarcely imaginable—we will continue on, in some
form. But in the emerging perfect storm of food stock declines, water
scarcity, climate disruption, and energy shortfalls, there now exist
measurable global-scale threats to social order and basic living standards
that are the material bedrock of civic society as we recognize it.
The dramatic environmental changes underway on earth are already
impacting human social systems. Droughts, floods, and rising sea levels are
taking lives, damaging infrastructure, reducing crop yields and creating a
new global underclass of environmental refugees. The question is how
much more serious will these impacts become and how soon? There are no
reassuring answers if we continue on a business-as-usual path. One thing
about sustainability in the twenty-first century is certain: individual nations
and the international community together will need to both mitigate the
projected declines of the planet’s ecosystems, and at the same time adapt to
those that are irreversible. As one popular sustainability policy mantra has
it: “we must strive to avoid the unmanageable, while managing the
unavoidable.”
The environmental historian Sing Chew sees in the cluster of environmental
crises of the early 21° century the hallmarks of a potential new Dark Age,
that is, a period of conflict, resource scarcity and cultural impoverishment
such as has afflicted the global human community only a few times over the
past five millennia. The goal of sustainability, in these terms, is clear and
non-controversial: to avoid a new and scaled-up Dark Age in which the
aspirations of billions of people, both living and yet unborn, face brutal
constraints. The implications of sustainability, in this sense, extend well
beyond what might ordinarily considered “green” issues, such as preserving
rainforests or saving whales. Sustainability is a human and social issue as
much as it is “environmental.” Sustainability is about people, the habitats
we depend on for services vital to us, and our ability to maintain culturally
rich civic societies free from perennial crises in food, water, and energy
supplies.
Glossary
adaptation
Focuses on the need for strategies to deal with the climate change that
is unavoidable because of increased carbon already in the atmosphere.
mitigation
Refers to the importance of reducing carbon emissions so as to prevent
further, catastrophic changes in the climate system.
It’s Not Easy Being Green: Anti-Environmental Discourse, Behavior, and
Ideology
In this module, you will learn about the complex connections that tie our
modern lifestyles and the consumption of goods to human and
environmental impacts across the world.
Learning Objectives
After reading this module, students should be able to
e understand the complex connections that tie our modern lifestyles and
the consumption of goods to human and environmental impacts across
the world
e relate our habits of consumption to the long history of human social
development on evolutionary time scales
e apply the working distinction between “society” and “culture” outlined
in this section to explain the different and often conflictual attitudes
toward the environment that exist today
Introduction
The consensus view among scientists and professional elites in the early
twenty-first century, as it has been among environmental activists for a
much longer time, is that our globalized industrial world system is on an
unsustainable path. Inherent in this view is a stern judgment of the recent
past: we have not adapted well, as a species, to the fruits of our own
brilliant technological accomplishments, in particular, to the harnessing of
fossil fuels to power transport and industry.
Taking the long view of human evolution, it is not surprising to find that we
are imperfectly adapted to our modern industrialized world of cars,
computers, and teeming cities, or that human societies organized for so
many millennia around the problem of scarcity should treat a sudden
abundance of resources with the glee of a kid in a candy store. In
evolutionary terms, we have simply not had sufficient time to adapt to the
windfall of change. Though rapid advances in the biophysical sciences in
recent decades mean that we mostly understandour maladaptation to
industrialization and the great dangers it poses, our political decision-
making and consumption patterns have barely changed on the basis of this
understanding. This sobering fact tells us that, at this moment in human
history, social behavior and political decision-making are not being driven
by knowledge, but rather by entrenched attitudes that perpetuate an
unsustainable drawdown of earth’s resources. In short, human decision
making and consumption of material goods in our fossil-fuel age continues
to largely take place outside of an awareness of the strained and finite
nature of our planet’s ecosystem services.
It is the character of modern consumer society to promote the idea that
nothing is connected, that the jeans we wear, or the food we eat, are matters
of personal choice without any greater context beyond a concern for
immediate pleasure and peer approval. Sustainability, by contrast, teaches
that everything is connected. That favorite pair of jeans, for instance, is
dependent on cheap labor in developing countries, on heavily fertilized
cotton plantations, and enormous volumes of water expended throughout
the jeans’ lifecycle, from the irrigation to grow the cotton to the washing
machine that cleans them. Or let’s take that “cheap” fast food lunch from
yesterday: it most likely contained processed soybeans from a recently
cleared stretch of the Amazon rainforest, and artificial sweeteners made
from corn whose enormous production quotas are subsidized by
government tax revenues. The corn-based sweetener, in turn, turns out to be
a principal cause of the national obesity epidemic, a key contributor to
spiraling health care costs. Thus the “value meal” turns out not to be so
economical after all, once the systems-wide effects are factored in.
A twenty minute video, The Story of Stuff, tells the complicated story of
how our "stuff" moves from extraction to sale to disposal.
The Story of Stuff
[missing_resource: http://www.youtube.com/v/9GorqroigqM?
version=3&hl=en_US]
Fast Food Industry's Environmental Impact? Here’s
food for thought. Though we are accustomed to
measuring the impact of a fast food diet on our physical
health, there is much less readily available information
on the global network of agricultural providers that
supports the fast food industry, and on its
environmental impacts on land use, water resources,
and human communities. Source: Created by
CrazyRob926
Connectivity
To think about sustainability in these terms may sound exhausting. But
because we live in a world characterized by connectivity, that is,
bycomplex chains linking our everyday lives to distant strangers and
ecosystems in far flung regions of the earth, we have no choice. In the end,
we must adapt our thinking to a complex, connected model of the world and
our place in it. Persisting with only simple, consumerist frames of
understanding—“I look great!” “This tastes delicious!”—for a complex
world of remote impacts and finite resources renders us increasingly
vulnerable to episodes of what ecologists call system collapse, that is, to the
sudden breakdown of ecosystem services we rely upon for our life’s staple
provisions.
In the early twenty-first century, vulnerability to these system collapses
varies greatly according to where one lives. A long-term drought in India
might bring the reality of aquifer depletion or climate change home to tens
of thousands of people driven from their land, while the life of a suburban
American teenager is not obviously affected by any resource crisis. But this
gap will narrow in the coming years. Overwhelming scientific evidence
points to rapidly increasing strains this century on our systems of food,
water, and energy provision as well as on the seasonable weather to which
we have adapted our agricultural and urban regions. In time, no one will
enjoy the luxury of remaining oblivious to the challenges of sustainability.
Drought, for example, is one of the primary indices of global ecosystem
stress, and arguably the most important to humans. According to the United
Nations Food and Agriculture Organization, without wholesale reformation
of water management practices on a global scale, two-thirds of the world’s
population will face water shortages by 2025, including densely populated
regions of the United States.
So how did we arrive at this point? Without you or I ever consciously
choosing to live unsustainably, how has it nevertheless come about that we
face environmental crises of global scale, circumstances that will so
decisively shape our lives and those of our children? Here’s one explanatory
narrative, framed by the long view of human evolution.
Since the emergence of the first proto-human communities in Africa
millions of years ago, we have spent over 99% of evolutionary time as
nomadic hunters and gatherers. A fraction of the balance of our time on
earth spans the 10,000 years of human agriculture, since the end of the last
Ice Age. In turn, only a third of that fractional period has witnessed the
emergence of the institutions and technologies—writing, money,
mathematics, etc.—that we associate with human “civilization.” And lastly,
at the very tip of the evolutionary timeline, no more than a blink of human
species history, we find the development of the modern industrialized
society we inhabit. Look around you. Observe for a moment all that is
familiar in your immediate surroundings: the streetscape and buildings
visible through the window, the plastic furnishings in the room, and the
blinking gadgets within arm’s length of where you sit. All of it is
profoundly “new” to human beings; to all but a handful of the tens of
thousands of generations of human beings that have preceded us, this
everyday scene would appear baffling and frightening, as if from another
planet.
Normalization
In this sense, the real miracle of human evolution is that cars, computers,
and cities appear so normal to us, even sometimes “boring” and
monotonous! Our perception of the extraordinary, rapid changes in human
societies in the past two centuries—even the past half-century—is deadened
by virtue of what is our greatest evolutionary acquirement, namely
normalization, an adaptive survival strategy fundamental to human success
over the millennia. The ability to accept, analyze, and adapt to often
fluctuating circumstances is our great strength as a species. But at this point
in human history it is also a grave weakness, what, in the language of Greek
tragedy might be called a “fatal flaw.”
To offer an analogy, for many centuries slavery appeared normal to most
people across the world—until the late eighteenth century, when a handful
of humanitarian activists in Britain began the long and difficult process of
de-normalizing human bondage in the eyes of their compatriots. The task of
sustainability ethics is analogous, and no less difficult, in that it lays out the
argument for wholesale and disruptive attitude adjustment and behavior
change in the general population. Given the long-term adaptation of the
human species to the imperatives of hunter-gathering, our decision-making
priorities and consumption drives still tend toward the simple necessities,
based on the presumption of relative and seasonal scarcity, and with little
emotional or social reward for restraint in the face of plenty, for viewing our
choices in global terms, or for measuring their impacts on future
generations.
A working distinction between the historical evolution of human society
and human culture is useful to understanding the social and psychological
obstacles to achieving sustainability. As both individuals and societies, we
work hard to insulate ourselves from unpleasant surprises, shocks, and
disorder. We crave “security,” and our legal and economic institutions
accordingly have evolved over the millennia to form a buffer against what
Shakespeare’s Hamlet called “the thousand natural shocks that flesh is heir
to.” For instance, the law protects us from violent physical harm (ideally),
while insurance policies safeguard us from financial ruin in the event of an
unexpected calamity.
In one sense, this security priority has determined the basic evolution of
human societies, particularly the decisive transition 10,000 years ago from
the variable and risky life of nomadic hunter communities to sedentary
farming based on an anticipated stability of seasonal yields. Of course, the
shift to agriculture only partially satisfied the human desire for security as
farming communities remained vulnerable to changing climatic conditions
and territorial warfare. Global industrialization, however, while it has
rendered vast populations marginal and vulnerable, has offered its
beneficiaries the most secure insulation yet enjoyed by humans against “the
slings and arrows of outrageous fortune.” This success has been a double-
edged sword, however, not least because the industrialized cocoon of our
modern consumer lifestyles relentlessly promotes the notion that we have
transcended our dependence on the earth’s basic resources. As it stands, we
look at our highly complex, industrialized world, and adapt our
expectations and desires to its rewards. It is never our first instinct to ask
whether the system of rewards itself might be unsustainable and collapse at
some future time as a result of our eager participation.
Sustainability Obstacles and Support
In terms of the evolutionary argument I am outlining here, our ability to
grasp the sustainability imperative faces two serious obstacles. The first is
psychological, namely the inherited mental frameworks that reward us for
the normalization and simplification of complex realities. The second is
social, namely our economic and institutional arrangements designed to
protect us from material wants, as well as from risk, shock, disorder and
violent change. Both these psychological and social features of our lives
militate against an ecological, systems-based worldview.
Luckily, our cultural institutions have evolved to offer a counterweight to
the complacency and inertia encouraged by the other simple, security-
focused principles governing our lives. If society is founded upon the
principle of security, and promotes our complacent feeling of independence
from the natural world, we might think of culture as the conscience of
society. What culture does, particularly in the arts and sciences, is remind us
of our frailty as human beings, our vulnerability to shocks and sudden
changes, and our connectedness to the earth’s natural systems. In this sense,
the arts and sciences, though we conventionally view them as opposites, in
fact perform the same social function: they remind us of what lies beyond
the dominant security paradigm of our societies—which tends to a
simplified and binary view of human being and nature—by bringing us
closer to a complex, systemic understanding of how the natural world
works and our embeddedness within it. Whether by means of an essay on
plant biology, or a stage play about family breakdown (like Hamlet), the
arts and sciences model complex worlds and the systemic interrelations that
shape our lives. They expose complexities and connectivities in our world,
and emphasize the material consequences of our actions to which we might
otherwise remain oblivious. The close relation between the arts and
sciences in the Western world is evidenced by the fact that their concerns
have largely mirrored each other over time, from the ordered, hierarchical
worldview in the classical and early modern periods, to the post-modern
focus on connectivity, chaos, and emergence.
Life in the pre-modern world, in the memorable words of the English
philosopher Thomas Hobbes, was mostly “nasty, brutish, and short.” By
contrast, social and economic evolution has bestowed the inhabitants of the
twenty-first century industrialized world with a lifestyle uniquely (though
of course not wholly) insulated from physical hardship, infectious disease,
and chronic violence. This insulation has come at a cost, however, namely
our disconnection from the basic support systems of life: food, water and
energy. This is a very recent development. At the beginning of the 20"
century, for example, almost half of Americans grew up on farms. Now,
fewer than two percent do. We experience the staples of life only at their
service endpoints: the supermarket, the faucet, the gas station. In this
context, the real-world sources of food, water, and energy do not seem
important, while supplies appear limitless. We are not prepared for the
inevitable shortages of the future.
On the positive side, it is possible to imagine that the citizens of the
developed world might rapidly reconnect to a systems view of natural
resources. One product of our long species evolution as hunters and
agricultural land managers is an adaptive trait the ecologist E. O. Wilson
has called “biophilia,” that is, a love for the natural world that provides for
us. In the few centuries of our fossil fuel modernity, this biophilia has
become increasingly aestheticized and commodified—as landscape art, or
nature tourism—and consequently marginalized from core social and
economic decision structures. In the emerging age of environmental decline
and resource scarcity, however, our inherited biophilia will play a key role
in energizing the reform of industrialized societies toward a sustainable,
renewable resource and energy future.
Review Questions
Exercise:
Problem:
How has the human capacity for normalization both helped and
hindered social development, and what are its implications for
sustainable reform of our industries, infrastructure, and way of life?
Exercise:
Problem:
Take an everyday consumer item—running shoes, or a cup of coffee—
and briefly chart its course through the global consumer economy from
the production of its materials to its disposal. What are its
environmental impacts, and how might they be reduced?
Glossary
Connectivity
An important feature of complex systems. Connections exist between
even apparently remote and disparate things. For example, drought in
Australia might impact the price of bread in Egypt, which in turn has
repercussions for U.S. foreign policy.
Normalization
An acquired evolutionary trait characteristic of human beings, whereby
even radical changes are quickly adapted to and represented as normal.
The Industrialization of Nature: A Modern History (1500 to the present)
In this module, you will learn about the industrialization of nature by
examining a timeline of global economic development and relating the
concept of externalization of environmental costs to industrial development.
Learning Objectives
After reading this module, students should be able to
e reproduce a basic timeline of global economic development since
1500, and outline the historical webs of trade linking sources of major
raw materials—e.g. spices, cotton, oil—to their consumer markets on a
world map
e define the historical development of core and periphery nations in the
world economy
e understand the concept of externalization of environmental costs, and
its role as a principle driver of unsustainable industrial development
Introduction
It is a measure of our powers of normalization that we in the developed
world take the existence of cheap energy, clean water, abundant food, and
international travel so much for granted, when they are such recent
endowments for humanity, and even now are at the disposal of considerably
less than half the global population. It is a constant surprise to us that a
situation so “normal” could be having such abnormal effects on the
biosphere—degrading land, water, air, and the vital ecosystems hosting
animals and fish. How did we get here? How can we square such apparent
plenty with warnings of collapse?
Population
People (billion)
7
6
5
4
1750 1800 1850 1900 1950 2000
@ “4 3 US Bureau of the Census (2000) International database
CHANGE _—=—sIG BP. synthesis: Global Change and the Earth System, Steffen et al 2004
Population Growth Graph showing the rapid increase in human
population since the beginning of the Industrial Age, with exponential
rise since the mid-twentieth century. Source: IGBP synthesis: Global
Raw figures at least sketch the proportions of global change over the last
500 years. In 1500, even after several centuries of rapid population growth,
the global population was no more than 500 million, or less than half the
population of India today. It is now fourteen times as large, almost 7 billion.
Over the same period, global economic output has increased 120 times,
most of that growth occurring since 1820, and with the greatest acceleration
since 1950. This combination of rampant population and economic growth
since 1500 has naturally had major impacts on the earth’s natural resources
and ecosystem health. According to the United Nations Millennium
Ecosystem Assessment, by the beginning of the 21‘ century, 15 of the
world’s 24 ecosystems, from rainforests to aquifers to fisheries, were rated
in serious decline.
Economic Development
Fundamental to significant changes in human history has been social
reaction to resource scarcity. By 1500, Europeans, the first engineers of
global growth, had significantly cleared their forests, settled their most
productive agricultural lands, and negotiated their internal borders. And yet
even with large-scale internal development, Europe struggled to feed itself,
let alone to match the wealth of the then dominant global empires, namely
China and the Mughal States that stretched from the Spice Islands of
Southeast Asia to the busy ports of the Eastern Mediterranean. As a
consequence of resource scarcity, European states began to sponsor
explorations abroad, in quest initially for gold, silver, and other precious
metals to fill up their treasuries. Only over time did Europeans begin to
perceive in the New World the opportunities for remote agricultural
production as a source of income. Full-scale colonial settlement was an
even later idea.
The new “frontiers” of European economic development in the immediate
pre-industrial period 1500-1800 included tropical regions for plantation
crops, such as sugar, tobacco, cotton, rice, indigo, and opium, and temperate
zones for the cultivation and export of grains. The seagoing merchants of
Portugal, France, Spain, Britain and the Netherlands trawled the islands of
the East Indies for pepper and timber; established ports in India for
commerce in silk, cotton and indigo; exchanged silver for Chinese tea and
porcelain; traded sugar, tobacco, furs and rice in the Americas; and sailed to
West Africa for slaves and gold. The slave trade and plantation economies
of the Americas helped shift the center of global commerce from Asia to the
Atlantic, while the new oceangoing infrastructure also allowed for the
development of fisheries, particularly the lucrative whale industry. All these
commercial developments precipitated significant changes in their
respective ecosystems across the globe—deforestation and soil erosion in
particular—albeit on a far smaller scale compared with what was to come
with the harnessing of fossil fuel energy after 1800.
The 19" century witnessed the most rapid global economic growth seen
before or mostly since, built on the twin tracks of continued agricultural
expansion and the new “vertical” frontiers of fossil fuel and mineral
extraction that truly unleashed the transformative power of industrialization
on the global community and its diverse habitats. For the first time since the
human transition to agriculture more than 10,000 years before, a state’s
wealth did not depend on agricultural yields from contiguous lands, but
flowed rather from a variety of global sources, and derived from the
industrialization of primary products, such as cotton textiles, minerals and
timber. During this period, a binary, inequitable structure of international
relations began to take shape, with a core of industrializing nations in the
northern hemisphere increasingly exploiting the natural resources of
undeveloped periphery nations for the purposes of wealth creation.
a) Core
HEB Seru-Penphery
GBB Penphery
Othe*
World Trade
Trade Map, Late 20th Century This map shows the “core”
industrialized nations of the northern hemisphere, and the “periphery”
nations of the tropics and south dependent on subsistence agriculture
and natural resource extraction. This unequal relationship is the
product of hundreds of years of trade and economic globalization
Source: Created by Naboc1, based on a list in Christopher Chase-
Dunn, Yukio Kawano and Benjamin Brewer, Trade Globalization since
1795, American Sociological Review, 2000 February, Vol. 65
The Great Acceleration
Despite the impact of the world wars and economic depression on global
growth in the early 20" century, the new technological infrastructure of the
combustion engine and coal-powered electricity sponsored increased
productivity and the sanitization of growing urban centers. Infectious
diseases, the scourge of humanity for thousands of years, retreated, more
than compensating for losses in war, and the world’s population continued
to increase dramatically, doubling from 1 to 2 billion in 50 years, and with
it the ecological footprint of our single species.
Nothing, however, is to be compared with the multiplying environmental
impacts of human activities since 1950, a period dubbed by historians as
“The Great Acceleration.” In the words of the United Nations Millennium
Ecosystem Assessment, “over the past 50 years, humans have changed
ecosystems more rapidly and extensively than in any comparable period of
time in human history, largely to meet rapidly growing demands for food,
fresh water, timber, fiber, and fuel. This has resulted in a substantial and
largely irreversible loss in the diversity of life on Earth.” The post-WWII
global economic order promoted liberal and accelerated trade, capital
investment, and technological innovation tethered to consumer markets,
mostly free of environmental impact considerations. The resultant economic
growth, and the corresponding drawdown of natural resources, are
nonlinear in character, which is, exhibiting an unpredictable and
exponential rate of increase.
All systems, human and natural, are characterized by nonlinear change. We
are habituated to viewing our history as a legible story of “progress,”
governed by simple cause-and-effect and enacted by moral agents, with the
natural world as a backdrop to scenes of human triumph and tragedy. But
history, from a sustainability viewpoint, is ecological rather than dramatic
or moral; that is, human events exhibit the same patterns of systems
connectivity, complexity, and non-linear transformation that we observe in
the organic world, from the genetic makeup of viruses to continental
weather systems. The history of the world since 1950 is one such example,
when certain pre-existing conditions—petroleum-based energy systems,
technological infrastructure, advanced knowledge-based institutions and
practices, and population increase—synergized to create a period of
incredible global growth and transformation that could not have been
predicted at the outset based upon those conditions alone. This unforeseen
Great Acceleration has brought billions of human beings into the world, and
created wealth and prosperity for many. But nonlinear changes are for the
bad as well as the good, and the negative impacts of the human “triumph”
of postwar growth have been felt across the biosphere. I will briefly detail
the human causes of the following, itself only a selective list: soil
degradation, deforestation, wetlands drainage and damming, air pollution
and climate change.
Soil Degradation
Since the transition to agriculture 10,000 years ago, human communities
have struggled against the reality that soil suffers nutrient depletion through
constant plowing and harvesting (mostly nitrogen loss). The specter of a
significant die-off in human population owing to stagnant crop yields was
averted in the 1970s by the so-called “Green Revolution,” which, through
the engineering of new crop varieties, large-scale irrigation projects, and the
massive application of petroleum-based fertilizers to supplement nitrogen,
increased staple crop production with such success that the numbers
suffering malnutrition actually declined worldwide in the last two decades
of the 20" century, from 1.9 to 1.4 billion, even as the world’s population
increased at 100 times background rates, to 6 billion. The prospects for
expanding those gains in the new century are nevertheless threatened by the
success of industrial agriculture itself. Soil depletion, declining water
resources, and the diminishing returns of fertilizer technology—all the
products of a half-century of industrial agriculture—have seen increases in
crop yields level off. At the same time, growing populations in developing
countries have seen increasing clearance of fragile and marginal agricultural
lands to house the rural poor.
It has been estimated that industrial fertilizers have increased the planet’s
human carrying capacity by two billion people. Unfortunately, most of the
chemical fertilizer applied to soils does not nourish the crop as intended, but
rather enters the hydrological system, polluting aquifers, streams, and
ultimately the oceans with an oversupply of nutrients, and ultimately
draining the oxygen necessary to support aquatic life. As for the impact of
fertilizers on soil productivity, this diminishes over time, requiring the
application of ever greater quantities in order to maintain yields.
Deforestation
Arguably the biggest losers from 20" century economic growth were the
forests of the world’s tropical regions and their non-human inhabitants.
Across Africa, Asia, and the Americas, approximately one-third of forest
cover has been lost. Because about half of the world’s species inhabits
tropical rainforests, these clearances have had a devastating impact on
biodiversity, with extinction rates now greater than they have been since
the end of the dinosaur era, 65 million years ago. Much of the cleared land
was converted to agriculture, so that the amount of irrigated soils increased
fivefold over the century, from 50 to 250m hectares. Fully 40% of the
terrestrial earth’s total organic output is currently committed to human use.
But we are now reaching the ceiling of productive land expansion, in terms
of sheer area, while the continued productivity of arable land is threatened
by salinity, acidity and toxic metal levels that have now degraded soils
across one third of the earth’s surface, some of them irreversibly.
Global Forest Map Since the middle of the twentieth century, the
global logging industry, and hence large-scale deforestation, has
shifted from the North Atlantic countries to the forests of tropical
regions such as Indonesia and the Amazon Basin in Latin America.
This tropical “green belt” is now rapidly diminishing, with
devastating consequences for local ecosystems, water resources, and
global climate. Source: NASA
Wetlands Drainage and Damming
Meanwhile, the worlds’ vital wetlands, until recently viewed as useless
swamps, have been ruthlessly drained—15% worldwide, but over half in
Europe and North America. The draining of wetlands has gone hand in
hand with large-scale hydro-engineering projects that proliferated through
the last century, such that now some two-thirds of the world’s fresh water
passes through dam systems, while rivers have been blocked, channeled,
and re-routed to provide energy, irrigation for farming, and water for urban
development. The long-term impacts of these projects were rarely
considered in the planning stages, and collectively they constitute a
wholesale re-engineering of the planet’s hydrological system in ways that
will be difficult to adapt to the population growth demands and changing
climatic conditions of the 21° century. As for the world’s oceans, these
increasingly show signs of acidification due to carbon emissions,
threatening the aquatic food chain and fish stocks for human consumption,
while on the surface, the oceans now serve as a global conveyor belt for
colossal amounts of non-degradable plastic debris.
Mississippi Watershed Map The
catchment area of the Mississippi
River covers almost 40% of the
U.S. continental landmass,
collecting freshwater from 32
states. Included in the runoff that
feeds the river system are large
quantities of agricultural fertilizer
and other chemicals that
eventually drain into the Gulf of
Mexico, creating an ever-growing
“dead zone.” Source:
Environmental Protection Agency
Air Pollution
In many parts of the world, pollution of the air by industrial particles is now
less a problem than it was a century ago, when newspapers lamented the
“black snow” over Chicago. This is due to concerted efforts by a clean air
caucus of international scope that arose in the 1940s and gained significant
political influence with the emergence of the environmental movement in
the 1970s. The impact of the post-70s environmental movement on the
quality of air and water, mostly in the West, but also developing countries
such as India, is the most hopeful precedent we have that the sustainability
issues facing the world in the new century might yet be overcome, given
political will and organization equal to the task.
Climate Change
Air pollution is still a major problem in the megacities of the developing
world, however, while a global change in air chemistry—an increase of
40% in the carbon load of the atmosphere since industrialization—is
ushering in an era of accelerated climate change. This era will be
characterized by increased droughts and floods, higher sea levels, and
extreme weather events, unevenly and unpredictably distributed across the
globe, with the highest initial impact in regions that, in economic and
infrastructural terms, can least support climate disruption (for example, sub-
Saharan Africa). The environmental historian J. R. McNeil estimates that
between 25 and 40 million people died from air pollution in the 20"
century. The death toll arising from climate change in the 21°‘ century is
difficult to predict, but given the scale of the disruption to weather systems
on which especially marginal states depend, it is likely to be on a much
larger scale.
Summary
From the Portuguese sea merchants of the 16" century in quest of silver and
spices from Asia, to the multinational oil companies of today seeking to
drill in ever more remote and fragile undersea regions, the dominant view
driving global economic growth over the last half millennium has been
instrumentalist, that is, of the world’s ecosystems as alternately a source of
raw materials (foods, energy, minerals) and a dump for the wastes produced
by the industrialization and consumption of those materials. The
instrumentalist economic belief system of the modern era, and particularly
the Industrial Age, is based on models of perennial growth, and measures
the value of ecosystems according to their production of resources
maximized for efficiency and hence profit. In this prevailing system, the
cost of resource extraction to the ecosystem itself is traditionally not
factored into the product and shareholder values of the industry. These costs
are, in economic terms, externalized.
A future economics of sustainability, by contrast, would prioritize the
management of ecosystems for resilience rather than pure capital efficiency,
and would incorporate the cost of ecosystem management into the pricing
of goods. In the view of many sustainability theorists, dismantling the
system of “unnatural” subsidization of consumer goods that has developed
over the last century in particular is the key to a sustainable future. Only a
reformed economic system of natural pricing, whereby environmental costs
are reflected in the price of products in the global supermarket, will alter
consumer behavior at the scale necessary to ensure economic and
environmental objectives are in stable alignment, rather than in constant
conflict. As always in the sustainability paradigm, there are tradeoffs. A
future economy built on the principle of resilience would be very different
from that prevalent in the economic world system of the last 500 years in
that its managers would accept reduced productivity and efficiency in
exchange for the long-term vitality of the resource systems on which it
depends.
Review Questions
Exercise:
Problem:
What are the major technological and economic developments since
1500 that have placed an increased strain on the planet’s ecosystem
services? What is the role of carbon-based energy systems in that
history?
Exercise:
Problem:
What is the so-called Great Acceleration of the 20" century? What
were its principal social features and environmental impacts?
Exercise:
Problem:
What is the Green Revolution? What were its successes, and what
problems has it created?
Glossary
biodiversity and extinction
Thriving ecosystems are characterized by diverse plant and animal
populations; there is, therefore, a strong correlation between current
ecosystem decline globally, and the rate of extinction of species, which
is in the order of a thousand times that of background rates. This has
prompted scientists to label the current period the Sixth Mass
Extinction in the long history of the biosphere, and the first since the
end of the dinosaurs.
externalization
The process by which costs inherent to the production of goods—
particularly environmental costs—are not included in the actual price
paid.
instrumentalist
An attitude to environmental resources characteristic of the last 500-
year period of global human economic development, whereby
ecosystem provisions—water, minerals, oil and gas, etc.—are
perceived only in terms of their use value to human beings, rather than
as integral elements of a wider natural system.
nonlinear
Changes in a system are nonlinear when they exhibit sudden changes
in rate of increase or decline. The population of a particular tropical
frog species, for example, may suddenly crash as a result of warming
temperatures, rather than show gradual decline.
Sustainability Studies: A Systems Literacy Approach
In this module, you will learn how systems literacy is tailored specifically
to the understanding and remedy of environmental problems, and the ways
in which it differs from traditional disciplinary approaches to academic
learning.
Learning Objectives
After reading this module, students should be able to
e define systems literacy, how it is tailored specifically to the
understanding and remedy of environmental problems, and the ways in
which it differs from traditional disciplinary approaches to academic
learning
¢ define bio-complexity as a scientific principle, and its importance as a
concept and method for students in the environmental humanities and
social sciences
e identify a potential research project that would embrace applications of
one or more of the following sustainability key terms: resilience and
vulnerability, product loops and lifecycles, and carbon neutrality
Introduction
Transition to a sustainable resource economy is a dauntingly large and
complex project, and will increasingly drive research and policy agendas
across academia, government, and industry through the twenty-first century.
To theorize sustainability, in an academic setting, is not to diminish or
marginalize it. On the contrary, the stakes for sustainability education could
not be higher. The relative success or failure of sustainability education in
the coming decades, and its influence on government and industry practices
worldwide, will be felt in the daily lives of billions of people both living
and not yet born.
The core of sustainability studies, in the academic sense, is systems
literacy—a simple definition, but with complex implications. Multiple
indicators tell us that the global resource boom is now reaching a breaking
point. The simple ethos of economic growth—“more is better”—is not
sustainable in a world of complex food, water and energy systems suffering
decline. The grand challenge of sustainability is to integrate our decision-
making and consumption patterns—along with the need for economic
viability— within a sustainable worldview. This will not happen by dumb
luck. It will require, first and foremost, proper education. In the nineteenth
and twentieth centuries, universal literacy—reading and writing—was the
catch-cry of education reformers. In the twenty-first century, a new global
literacy campaign is needed, this time systems literacy, to promote a basic
understanding of the complex interdependency of human and natural
systems.
Here I will lay out the historical basis for this definition of sustainability in
terms of systems literacy, and offer specific examples of how to approach
issues of sustainability from a systems-based viewpoint. Systems literacy,
as a fundamental goal of higher education, represents the natural evolution
of interdisciplinarity, which encourages students to explore connections
between traditionally isolated disciplines and has been a reformist
educational priority for several decades in the United States. Systems
literacy is an evolved form of cross-disciplinary practice, calling for
intellectual competence (not necessarily command) in a variety of fields in
order to better address specific real-world environmental problems.
For instance, a student’s research into deforestation of the Amazon under a
sustainability studies paradigm would require investigation in a variety of
fields not normally brought together under the traditional disciplinary
regime. These fields might include plant biology, hydrology, and
climatology, alongside economics, sociology, and the history and literature
of post-colonial Brazil. Systems literacy, in a nutshell, combines the study
of social history and cultural discourses with a technical understanding of
ecosystem processes. Only this combination offers a comprehensive view of
real-world environmental challenges as they are unfolding in the twenty-
first century.
From the viewpoint of systems literacy sustainability studies works on two
planes at once. Students of sustainability both acknowledge the absolute
interdependence of human and natural systems— indeed that human beings
and all their works are nothing if not natural—while at the same time
recognizing that to solve our environmental problems we must often speak
of the natural world and human societies as if they were separate entities
governed by different rules. For instance, it is very useful to examine
aspects of our human system as diachronic—as progressively evolving
over historical time—while viewing natural systems more according to
synchronic patterns of repetition and equilibrium. The diachronic features
of human social evolution since 1500 would include the history of trade and
finance, colonization and frontier development, and technology and
urbanization, while examples of nature’s synchronicity would be
exemplified in the migratory patterns of birds, plant and animal
reproduction, or the microbial ecology of a lake or river. A diachronic view
looks at the changes in a system over time, while the synchronic view
examines the interrelated parts of the system at any given moment,
assuming a stable state.
While the distinction between diachronic and synchronic systems is in some
sense artificial, it does highlight the structural inevitability of dysfunction
when the two interlocked systems operate on different timelines and
principles. The early twentieth century appetite for rubber to service the
emerging automobile industry, for instance, marks an important chapter in
the “heroic” history of human technology, while signifying a very different
transition in the history of forest ecosystems in Asia and Latin America.
Human history since the agricultural transition 10,000 years ago, and ona
much more dramatic scale in the last two hundred years, is full of such
examples of new human technologies creating sudden, overwhelming
demand for a natural resource previously ignored, and reshaping entire
ecosystems over large areas in order to extract, transport and industrialize
the newly commodified material.
Biocomplexity
For students in the humanities and social sciences, sustainability studies
requires adoption of a new conceptual vocabulary drawn from the
ecological sciences. Among the most important of these concepts is
complexity. Biocomplexity—the chaotically variable interaction of organic
elements on multiple scales—is the defining characteristic of all
ecosystems, inclusive of humans. Biocomplexity science seeks to
understand this nonlinear functioning of elements across multiple scales of
time and space, from the molecular to the intercontinental, from the
microsecond to millennia and deep time. Such an approach hasn’t been
possible until very recently. For example, only since the development of
(affordable) genomic sequencing in the last decade have biologists begun to
investigate how environments regulate gene functions, and how changes in
biophysical conditions place pressure on species selection and drive
evolution.
re)
Habitat | A#~ . » Planetary
—
—
ame
Bala
mwesdl
(-™
t=
—)
(+)
The Biocomplexity Spiral The biocomplexity spiral
illustrates the concept of biocomplexity, the chaotically
variable interaction of organic elements on multiple
scales. Source: U.S. National Science Foundation
How is the concept of complexity important to sustainability studies? To
offer one example, a biocomplexity paradigm offers the opportunity to
better understand and defend biodiversity, a core environmental concern.
Even with the rapid increase in knowledge in the biophysical sciences in
recent decades, vast gaps exist in our understanding of natural processes
and human impacts upon them. Surprisingly little is known, for example,
about the susceptibilities of species populations to environmental change or,
conversely, how preserving biodiversity might enhance the resilience of an
ecosystem. In contrast to the largely reductionist practices of twentieth-
century science, which have obscured these interrelationships, the new
biocomplexity science begins with presumptions of ignorance, and from
there goes on to map complexity, measure environmental impacts, quantify
risk and resilience, and offer quantitative arguments for the importance of
biodiversity. Such arguments, as a scientific supplement to more
conventional, emotive appeals for the protection of wildlife, might then
form the basis for progressive sustainability policy.
But such data-gathering projects are also breathtaking in the demands they
place on analysis. The information accumulated is constant and
overwhelming in volume, and the methods by which to process and
operationalize the data toward sustainable practices have either not yet been
devised or are imperfectly integrated within academic research structures
and the policy-making engines of government and industry. To elaborate
those methods requires a humanistic as well as scientific vision, a need to
understand complex interactions from the molecular to the institutional and
societal level.
A practical example of biocomplexity as the frame for studies in
environmental sustainability are the subtle linkages between the hypoxic
“dead zone” in the Gulf of Mexico and farming practices in the Mississippi
River watershed. To understand the impact of hydro-engineered irrigation,
nitrogen fertilizer, drainage, and deforestation in the Midwest on the
fisheries of the Gulf is a classic biocomplexity problem, requiring data
merging between a host of scientific specialists, from hydrologists to
chemists, botanists, geologists, zoologists and engineers. Even at the
conclusion of such a study, however, the human dimension remains to be
explored, specifically, how industry, policy, culture and the law have
interacted, on decadal time-scales, to degrade the tightly coupled riverine-
ocean system of the Mississippi Gulf. A quantitative approach only goes so
far. At a key moment in the process, fact accumulation must give way to the
work of narrative, to the humanistic description of desires, histories, and
discourses as they have governed, in this instance, land and water use in the
Mississippi Gulf region.
To complexity should be added the terms resilience and vulnerability, as
core concepts of sustainability studies. The resilience of a system—let’s
take for example, the wildlife of the Arctic Circle—refers to the self-
renewing stability of that system, its ability to rebound from shocks and
threats within the range of natural variability. The vulnerability of Artic
wildlife, conversely, refers to the point at which resilience is eroded to
breaking point. Warming temperatures in the Arctic, many times the global
average, now threaten the habitats of polar bear and walruses, and are
altering the breeding and migratory habits of almost all northern wildlife
populations. The human communities of the Arctic are likewise
experiencing the threshold of their resilience through rising sea levels and
coastal erosion. Entire villages face evacuation and the traumatic prospect
of life as environmental refugees.
As mentioned earlier, we have grown accustomed to speaking of “nature”
or “the environment” as if they were somehow separate from us, something
that might dictate our choice of holiday destination or wall calendar, but
nothing else. A useful counter-metaphor for sustainability studies, to offset
this habitual view, is to think of human and natural systems in metabolic
terms. Like the human body, a modern city, for example, is an energy-
dependent system involving inputs and outputs. Every day, millions of tons
of natural resources (raw materials, consumer goods, food, water, energy)
are pumped into the world’s cities, which turn them out in the form of waste
(landfill, effluent, carbon emissions, etc.).
Unlike the human body, however, the metabolism of modern cities is not a
closed and self-sustaining system. Cities are consuming resources at a rate
that would require a planet one and a half times the size of Earth to sustain,
and are ejecting wastes into the land, water, and air that are further
degrading the planet’s ability to renew its vital reserves. Here, another body
metaphor—the environmental “footprint”—has become a popular means
for imagining sufficiency and excess in our consumption of resources. The
footprint metaphor is useful because it provides us an image measurement
of both our own consumption volume and the environmental impact of the
goods and services we use. By making sure to consume less, and to utilize
only those goods and services with a responsibly low footprint, we in turn
reduce our own footprint on the planet. In important ways, the problem of
unsustainability is a problem of waste. From a purely instrumentalist or
consumerist viewpoint, waste is incidental or irrelevant to the value of a
product. A metabolic view of systems, by contrast, promotes sustainability
concepts such as closed loops and carbon neutrality for the things we
manufacture and consume, whereby there are no toxic remainders through
the entire lifecycle of a product. In this sense, systems literacy is as much a
habit or style of observing the everyday world as it is an academic principle
for the classroom. Because in the end, the fate of the world’s ecosystems
will depend not on what we learn in the classroom but on the extent to
which we integrate that learning in our lives beyond it: in our professional
practice and careers, and the lifestyle and consumer choices we make over
the coming years and decades. If systems literacy translates into a
worldview and way of life, then sustainability is possible.
Review Questions
Exercise:
Problem:
What are synchronicand diachronic views of time, and how does the
distinction help us to understand the relation between human and
natural systems, and to potentially rewrite history from an
environmental point of view?
Exercise:
Problem:
How is a bio-complex view of the relations between human and natural
systems central to sustainability, in both theory and practice?
Glossary
biocomplexity
A defining characteristic of living things and their relationships to each
other. The biocomplexity concept emphasizes the multiple dependent
connections within ecosystems, and between ecosystems and human
societies.
carbon neutrality
To be carbon neutral, the carbon emissions of a consumable product or
human activity must either not involve the consumption of carbon-
based energy (a difficult thing to achieve under our present regime), or
offset that consumption through the drawdown of an equivalent
amount of atmospheric carbon during its lifecycle.
closed loops
The sustainable reform of industrial production and waste management
emphasizes the recycling of materials back into the environment or
into the industrial cycle, that is, to eliminate the concept of waste
entirely.
diachronic/synchronic
A diachronic view of a system examines it evolution over time, while a
synchronic view is concerned with its characteristics at a single point
in time.
interdisciplinarity
A trend in higher education research and teaching of the last thirty
years that emphasizes the bridging of traditional disciplines, and that is
an essential framework for sustainability studies.
lifecycle
In terms of sustainability, the entire lifecycle of a product must be
measured for its environmental impact, not simply its point of
production, consumption, or disposal. A key aspect of general
sustainability education is the understanding of where goods originate,
the industrial processes required for their manufacture and transport,
and their fate after use.
metabolism and footprint
Two metaphors, related to the human body, for conceptualizing the
relationship between consumption and waste at the social level.
Metabolism emphasizes a system of inputs and outputs dependent
upon “energy” and measured according to the “health” of the whole,
while footprint is a popular metric for quantifying the environmental
impacts of goods, services, and lifestyles.
resilience and vulnerability
Important terms of measurement for the impact of environmental
change, particularly on human communities. The goal of sustainability
analysis and policy, at all levels, is to enhance the resilience of
communities to change, in other words, to mitigate their vulnerability.
systems literacy
An educational philosophy that emphasizes a student’s competence in
a wide variety of disciplines, so that he or she might better understand
the operations of those complex systems, both human and natural, that
underpin sustainability.
The Vulnerability of Industrialized Resource Systems: Two Case Studies
In this module, two case studies are introduced and our Faustian bargain
with Mother Nature is discussed.
Introduction
Sustainability is best viewed through specific examples, or case studies.
One way of conceiving sustainability is to think of it as a map that shows us
connections between apparently unrelated domains or sequences of events.
To cite an earlier example, what do the cornfields of Illinois have to do with
the decline of fisheries in the Gulf of Mexico? To the uneducated eye, there
is no relationship between two areas so remote from each other, but a
sustainable systems analysis will show the ecological chain linking the use
of chemical fertilizers in the Midwest, with toxic runoff into the Mississippi
Basin, with changes in the chemical composition in the Gulf of Mexico
(specifically oxygen depletion), to reduced fish populations, and finally to
economic and social stress on Gulf fishing communities. Here, I will look at
two case studies in greater detail, as a model for the systems analysis
approach to sustainability studies in the humanities. The first concerns the
alarming worldwide decline of bee populations since 2006, owing to a new
affliction named Colony Collapse Disorder (CCD). The second case study
examines the BP oil disaster in the Gulf of Mexico in 2010, considered in
the larger historical context of global oil dependency.
Our Faustian Bargain
Before the emergence of coal and later oil as highly efficient and adaptable
energy sources, human beings relied on mostly renewable sources of
energy, principally their own muscle power, supplemented to varying
degrees by the labor of domesticated farm animals, wood and peat for fuel,
and the harnessing of wind and water for milling and sailing. An
extraordinary and rapid transformation occurred with the extraction of
latent solar power from ancient organic deposits in the earth. On the eve of
industrialization, around 1800, the raw muscle power of human beings was
responsible for probably 70% of human energy expenditure, while slavery
—a brutal system for the concentration of that energy—functioned as a
comerstone of global economic growth. In the 1500-1800 period, in
addition to the ten million or more Africans transported to slave colonies in
the Americas, several times as many Indian and Chinese laborers, under
various regimes of servitude, migrated across the globe to answer labor
“shortages” within the globalizing Atlantic economy.
But technical improvements in the steam engine revolutionized this
longstanding energy equation. Already by 1800, a single engine could
produce power the equivalent of two hundred men. Today, a single worker,
embedded within a technologized, carbon-driven industry, takes a week to
produce what an 18" century laborer would take four years to do, while the
average middle-class household in the industrialized world consumes goods
and energy at a rate equivalent to having 100 slaves at their disposal round-
the-clock.
In the famous medieval story of Faust, a scholar who dabbles in black
magic sells his soul in exchange for extraordinary powers to satisfy his
every desire. The Faust story provides an excellent analogy for our 200-
year love affair with cheap fossil fuel energy. Our planetary carbon
endowment has provided us with extraordinary powers to bend space and
time to the shape of our desires and convenience, and fill it with cool stuff.
But petroleum and coal are finite resources, and such is the environmental
impact of our carbon-based Faustian lifestyle that scientists have now
awarded our industrial period, a mere blink in geological time, its own title
in the 4 billion year history of the planet: the Anthropocene. We are no
longer simply biological creatures, one species among thousands, but
biophysical agents, reshaping the ecology of the entire planet, and shaping
the fates of all species.
Faust and Mephistopheles Mephistopheles, the devil figure in
Goethe’s play Faust, tempts Faust with the exhilaration of flight.
From the air, it is easy for Faust to imagine himself lord of the earth,
with no limits to his powers. Source: Public Domain. Illustration by
Alphonse de Neuville
In short, we are all Fausts now, not the insignificant, powerless creatures we
sometime feel ourselves to be, but rather, the lords of the planet. How this
came to pass is an object lesson in complex diachronic evolution. Without
any single person deciding, or any law passed, or amendment made to the
constitution, we have transformed ourselves over but a few centuries from
one struggling species among all the rest, to being planetary managers, now
apparently exempted from the evolutionary struggle for survival with other
species, with the fate of animals, birds, fish, plants, the atmosphere, and
entire ecosystems in our hands. This Faustian power signals both our
strength and vulnerability. We are dependent on the very ecosystems we
dominate. That is, we have become carbon-dependent by choice, but we are
ecosystem-dependent by necessity. We may all be supermen and
wonderwomen relative to the poor powers of our forebears, but we still
require food, clean water, and clean air. The billion or more people on earth
currently not plugged into the carbon energy grid, and hence living in dire
poverty, need no reminding of this fact. Many of us in the developed world
do, however. Our civilization and lifestyles as human beings have changed
beyond recognition, but our biological needs are no different from our
species ancestors on the East African savannah a million years ago. In sum,
the lesson of the Faust story is hubris. We are not exempt from natural laws,
as Faust recklessly hoped.
To understand the impact of our fossil fuel based, industrialized society on
the planet we inhabit requires we think on dual time scales. The first is easy
enough, namely, the human scale of days and years. For example, consider
the time it takes for liquid petroleum to be extracted from the earth, refined,
transported to a gas station, and purchased by you in order to drive to
school or the shopping Mall. Or the time it takes for that sweater you buy at
the mall to be manufactured in China or Indonesia and transported
thousands of miles to the shelf you grab it from. This is an oil-dependent
process from beginning to end: from the petroleum-based fertilizers that
maximized the productive efficiency of the cotton plantation, to powering
the machinery in the factory, to the massive goods ship transporting your
Sweater across the oceans, to the lights in the store that illuminate your
sweater at the precise angle for it to catch your eye.
Now consider the second time scale, to which we are usually oblivious—
the thousands or millions of years it has taken for terrestrial carbon to form
those reserves of liquid petroleum that brought you your sweater. This is a
process describable only on a geological time scale, the costs of the
disruption to which have been wholly omitted from the sticker price of the
sweater. What are the environmental, and ultimately human costs that have
been externalized? In powering our modern societies through the
transference of the earth’s carbon reserves from long-term storage and
depositing it in the atmosphere and oceans, we have significantly altered
and destabilized the earth’s carbon cycle. There is now 40% more carbon in
the atmosphere and oceans than in 1800, at the outset of the industrial age.
The earth’s climate system is reacting accordingly, to accommodate the
increased nonterrestrial carbon load. The result is altered weather patterns,
increasing temperatures, glacial melt, and sharp increases in droughts,
floods, and wildfires. The cost to the global economy of these climate
disruptions this century has been projected in the trillions of dollars, even
before we consider the human costs of climate change in mortality,
homelessness, impoverishment, and social instability.
Extracting carbon from the earth, and transforming it into energy, fertilizers,
and products has enabled an almost magical transformation of human lives
on earth, as compared to those of our premodern ancestors. The house you
live in, the clothes you wear, the food you eat, the gadgets you use, and all
the dreams you dream for your future, are carbon-based dreams. These
amazing fossil-fuel energy sources—oil, coal, gas—have created modernity
itself: a crest of population growth, economic development, prosperity,
health and longevity, pulling millions out of poverty, and promoting, life,
liberty, and happiness. This modernity is truly a thing of wonder, involving
the high-speed mass transport of people, goods, and information across the
globe, day after day. Regardless of the season, it brings us apples from New
Zealand, avocadoes from Mexico, and tomatoes that have traveled an
average of 2000 miles to reach the “fresh produce” section of our
supermarkets. Having bought our groceries for the week, we jump in our
car and drive home. Because our species ancestors were both nomads and
settlers, we love our cars and homes with equal passion. We value both
mobility and rootedness. Done with roaming for the day, we cherish our
indoor lives in atmospherically controlled environments: cool when hot
outside, toasty when cold, light when dark, with digital devices plugged in
and available 24/7. A miraculous lifestyle when one sits back to reflect, and
all the result of ongoing carbon-intensive investments in human comfort
and convenience.
But it is also a 200-year chemistry experiment, with our planet as the
laboratory. We are carbon beings in our own molecular biology; we touch
and smell it; we trade, transport, and spill it; we consume and dispose of it
in the earth and air. Intensifying heat and storms and acidifying oceans are
carbon’s elemental answer to the questions we have posed to the earth
system’s resilience. Mother Nature is having her say, acting according to
her nature, and prompting us now to act according to our own mostly
forgotten natures—as beings dependent on our ecosystem habitat of sun,
rain, soil, plants, and animals, with no special allowance beyond the sudden
responsibility of reformed stewardship and management.
The 2010 BP oil spill in the Gulf of Mexico was a spectacular warning that
the 200-year era of cheap fossil fuel energy is drawing to a close. With
viable oil reserves likely to be exhausted in the next decade or so, and the
dangers to global climate associated with continued reliance on coal and
natural gas, the transition to a sustainable, low-carbon global economy—by
means that do not impoverish billions of people in the process—looms as
nothing less than the Great Cause of the 21%‘ century, and without doubt the
greatest challenge humanity has faced in its long residence on earth. The
stakes could not be higher for this task, which is of unprecedented scope
and complexity. If enormous human and financial resources were expended
in meeting the greatest challenges faced by the international community in
the 20" century—the defeat of fascism, and the hard-earned progress made
against poverty and infectious diseases—then the low-carbon sustainability
revolution of our century will require the same scale of resources and more.
At present, however, only a tiny fraction of those resources have been
committed.
Glossary
anthropocene
A term bestowed by Noble Laureate Paul Crutzen to describe the last
200-year period of human industrialization. The prefix “anthro” points
to the decisive impact of human population growth and technological
development on the planetary biosphere since 1800, as its principal
agents of change superceding all other factors.
Case Study: Agriculture and the Global Bee Colony Collapse
A case study about colony collapse disorder
Two thousand years ago, at the height of the Roman Empire, the poet Virgil
wrote lovingly about the practice of beekeeping, of cultivating the “aerial
honey and ambrosial dews” he called “gifts of heaven” (Georgics IV: 1-2).
Bees represent a gift to humanity even greater that Virgil knew. In addition
to satisfying the human appetite for honey, the Italian honeybee, Apis
melliflora, is the world’s most active pollinator, responsible for over 80 of
the world’s most common nongrain crops, including apples, berries,
almonds, macadamias, pumpkins, melons, canola, avocadoes, and also
coffee beans, broccoli and lettuce. Even the production chain of the
enormous meat and cotton industries relies at crucial points on the
ministrations of the humble honeybee. We depend on pollinated fruits, nuts
and seeds for a third of our caloric intake, and for vital vitamins, minerals
and antioxidants in our diet. In total, around 80% of the foods we eat are to
some degree the products of bee pollination, representing one third of total
agricultural output.
Given the $1 trillion value of pollinated produce, any threat to the health of
honey bees represents a serious threat to the human food chain—a classic
sustainability issue. With the industrialization of the global agricultural
system over the last 50 years—including crop monoculture and mass
fertilization—bees have indeed faced a series of threats to their ancient role,
the most recent of which, so-called Colony Collapse Disorder, is the most
serious yet.
Busy Bee Hive A forager honeybee comes in for landing at a healthy
hive, her legs dusted with pollen. Colony Collapse Disorder has
devastated tens of thousands of such hives. Source: Ken Thomas
In his poetic primer on beekeeping, Virgil includes a moving description of
a bee colony suffering mysterious decline:
" Observe the symptoms when they fall away" " And languish with
insensible decay." " They change their hue; with haggard eyes they stare . .
.""" The sick, for air, before the portal gasp," " Their feeble legs within each
other clasp," " Or idle in their empty hives remain," " Benumbed with cold,
and listless of their gain. (368-78)"
Beekeepers worldwide faced an even worse predicament in late 2006: the
mysterious disappearance of entire hives of bees. Over the winter,
honeybees enter a form of survival hibernation. Their populations suffer
inevitable losses, but these are replenished by the Queen’s renewed laying
of eggs once winter thaws. In the spring of 2007, however, hundreds of
thousands of colonies in the United States did not survive the winter. A full
30% of all honeybee colonies died. Each spring since has witnessed even
worse declines. Similar losses afflicted Europe and Asia. Worldwide,
millions of colonies and billions of bees have perished since 2006 on
account of the new bee plague.
Because the global commercial value of bee pollination is so enormous,
well-funded research into colony collapse began immediately. A number of
theories, some credible, some not, were quickly advanced. Several studies
pointed to new or enhanced viral strains, while others suggested the toxic
effect of industrial fertilization. Still others claimed that mobile phone
towers were interfering with the bees’ navigations systems. Because the
honeybee is a charismatic creature and features so prominently in our
cultural lore—we admire their industriousness, fear their stings, call our
loved ones “honey,” and talk much of Queen Bees—the story of colony
collapse was quickly taken up by the media. A flurry of news stories
announced CCD as an epic “disaster” and profound “mystery,” which was
true in simple terms, but which cast bee decline as a new and sudden
calamity for which some single culprit must be responsible.
The truth, as it is now unfolding, is more complex, and shows the
importance of viewing the interactions between human and natural
ecologies in systemic terms. In strictly pathogenic terms, CCD is caused by
the combination of a virus (called Iridoviridae or ITV) and a microsporidian
fungus called Nosema. The specific interaction between the pathogens, and
why they cause bees in their millions to vacate their hives, is not
understood. What is becoming clear, however, is the increasing burden
being placed on bees by the human agricultural system, a burden that has
rendered bees increasingly vulnerable to epidemic infection. Humans have
been keeping bees for eight thousand years, and European bees were at the
vanguard of the successful crop colonization of the Americas. But the
numbers of bees in the United States had already declined by a third since
1950 before the arrival of CCD, owing to various viral and mite
infestations, and the large scale changes in bee habitat and lifestyle.
Before the industrialization of farming, bees came from neighboring
wildlands to pollinate the diverse range of crops available to them on small
plots. But the conversion, for economic reasons, of arable land into
enormous monocrop properties in the last sixty years, and hence the
diminishment of proximate wildflower habitats, has necessitated a different
system, whereby bees are trucked around the country to service one crop at
a time, be it peppers in Florida, blueberries in Maine, or almonds in
California. At the height of the recent almond boom, the California crop
required almost the entire bee population of the United States to be fully
pollinated. Wholesale suburbanization is also to blame for the destruction of
the bees’ natural wildflower habitats. Be it a thousand acre cornfield or a
suburban street of well-tended green lawns, to a bees’ eyes, our modern
landscape, engineered to human needs, is mostly a desert.
Studies that have not identified specific culprits for CCD have nevertheless
shown the extent of the long-term decline in bee health wrought by their
conscription to industrial agriculture. For instance, researchers found no
fewer than 170 different pesticides in samples of American honeybees,
while other studies found that even bees not suffering CCD habitually carry
multiple viral strains in their systems. The combined toxic and viral load for
the average honeybee is enormous. In the words of Florida’s state apiarist,
“T’m surprised honey bees are alive at all.” (Jacobsen, 2008, p. 137) A
further study showed a decline in the immune systems of bees owing to lack
of diverse nutrition. Pollinating only almonds for weeks on end, then
travelling on a flatbed truck for hundreds of miles in order to service
another single crop, is not the lifestyle bees have adapted to over the near
80 million years of their existence. As Virgil warned, “First, for thy bees a
quiet station find.” The lives of modern bees have been anything but quiet,
and the enormous changes in their habitat and lifestyle have reduced their
species’ resilience.
The most important lesson of recent research into CCD is not the
identification of ITV and Nosema as the specific contributors, but the larger
picture it has provided of a system under multiple long-term stresses.
Complex systems, such as bee pollination and colony maintenance, are not
characterized by linear development, but rather by sudden, nonlinear
tipping point in a natural system on which humans depend, in which sudden
deterioration overtakes a population beyond its ability to rebound.
Everything seems fine, until it isn’t. One day we have almonds, berries,
melon, and coffee on our breakfast menu. The next day there’s a critical
shortage, and we can’t afford them.
In sustainability terms, bee colony collapse is a classic “human dimensions”
issue. CCD will not be “solved” simply by the development of a new anti-
viral drug or pesticide targeting the specific pathogens responsible. Part of
what has caused CCD is the immunosuppressive effects of generations of
pesticides developed to counter previous threats to bee populations, be they
microbes or mites. Our chemical intervention in the lifecycle of bees has, in
evolutionary terms, “selected” for a more vulnerable bee. That is, bees’
current lack of resilience is a systemic problem in our historical relationship
to bees, which dates back thousands of years, but which has altered
dramatically in the last fifty years in ways that now threaten collapse. And
this is to say nothing of the impact of bee colony collapse on other
pollination-dependent animals and birds, which would indeed be
catastrophic in biodiversity terms.
That we have adapted to bees, and they to us, is a deep cultural and
historical truth, not simply a sudden “disaster” requiring the scientific
solution of a “mystery.” In the light of sustainability systems analysis, the
bee crisis appears entirely predictable and the problem clear cut. The
difficulty arises in crafting strategies for how another complex system on a
massive scale, namely global agriculture, can be reformed in order to
prevent its collapse as one flow-on effect of the global crisis of the vital
honey bee. The incentive for such reform could not be more powerful. The
prospect of a future human diet without fruits, nuts and coffee is bleak
enough for citizens of the developed world and potentially fatal for millions
of others in the long term.
Review Questions
Exercise:
Problem:
What is the long history of the human relationship to bees, and what
radical changes in that relationship have occurred over the last fifty
years to bring it to the point of collapse? What are the implications of
bee colony collapse for the global food system?
References
Jacobsen, R. (2008). Fruitless Fall: The Collapse of the Honey Bee and the
Coming Agricultural Crisis. New York: Bloomsbury
Glossary
tipping point
The critical moment of nonlinear change whereby a system changes
suddenly from one state to another.
Case Study: Energy and the BP Oil Disaster
The BP Oil Disaster of 2010 is presented as an example of complex human
systems failure.
On the night of April 20, 2010, the Deepwater Horizon oil rig, one of
hundreds operating in the Gulf of Mexico, exploded, killing eleven men,
and placing one of the most rich and diverse coastal regions on earth in
imminent danger of petroleum poisoning. BP had been drilling in waters a
mile deep, and in the next two days, as the rig slowly sank, it tore a gash in
the pipe leading to the oil well on the ocean floor. Over the next three
months, two hundred million gallons of crude oil poured into the Gulf,
before the technological means could be found to seal the undersea well. It
was the worst environmental disaster in American history, and the largest
peacetime oil spill ever.
The Deepwater Horizon Oil Rig on Fire The Deepwater Horizon oil
rig on fire, April, 2010. It would later sink, precipitating the worst
environmental disaster in United States history. Source: Public
Domain U.S. Coast Guard
The BP oil disaster caused untold short- and long-term damage to the
region. The initial impact on the Gulf—the oil washing up on beaches from
Texas to Florida, and economic hardship caused by the closing down of
Gulf fishing—was covered closely by the news media. The longer term
impacts of the oil spill on wetlands erosion, and fish and wildlife
populations, however, will not likely receive as much attention.
Much public debate over the spill has focused on the specific causes of the
spill itself, and in apportioning responsibility. As with the example of bee
colony collapse, however, the search for simple, definitive causes can be
frustrating, because the breakdown is essentially systemic. Advanced
industries such as crop pollination and oil extraction involve highly
complex interactions among technological, governmental, economic, and
natural resource systems. With that complexity comes vulnerability. The
more complex a system, the more points at which its resiliency may be
suddenly exposed. In the case of the Deepwater Horizon rig, multiple
technological “safeguards” simply did not work, while poor and sometimes
corrupt government oversight of the rig’s operation also amplified the
vulnerability of the overall system—a case of governmental system failure
making technological failure in industry more likely, with an environmental
disaster as the result.
In hindsight, looking at all the weaknesses in the Gulf oil drilling system,
the BP spill appears inevitable. But predicting the specific vulnerabilities
within large, complex systems ahead of time can be next to impossible
because of the quantity of variables at work. Oil extraction takes place
within a culture of profit maximization and the normalization of risk, but in
the end, the lesson of BP oil disaster is more than a cautionary tale of
corporate recklessness and lax government oversight. The very fact that BP
was drilling under such risky conditions—a mile underwater, in quest of oil
another three miles under the ocean floor—is an expression of the global
demand for oil, the world’s most valuable energy resource. To understand
that demand, and the lengths to which the global energy industry will go to
meet it, regardless of environmental risk, requires the longer view of our
modern history as a fossil-fueled species.
Review Questions
Exercise:
Problem:
In what ways is the BP Oil Disaster of 2010 an example of complex
human systems failure, and what are its longer chains of causation in
the history of human industrialization?
Sustainability Ethics
In this module, the concept of the "tragedy of the commons" is related to
global environmental problems such as climate change and ocean
acidification. The principal of the intergenerational social contract is
described as the core or sustainability ethics.
Learning Objectives
After reading this module, students should be able to
e understand the principle of the intergenerational social contract at the
core of sustainability ethics
¢ define the global terms of responsibility for action on sustainability,
both the remote responsibilities applicable to you as an individual
consumer, and the historically-based concept of shared but
differentiated responsibilities driving negotiations between nations in
different hemispheres
Developing an Ethics of Sustainability
The 1987 United Nations Brundtland definition of sustainability embodies
an intergenerational contract: to provide for our present needs, while not
compromising the ability of future generations to meet their needs. It’s a
modest enough proposal on the face of it, but it challenges our current
expectations of the intergenerational contract: we expect each new
generation to be better off than their parents. Decades of technological
advancement and economic growth have created a mindset not satisfied
with “mere” sustainability. We might call it turbo-materialism or a
cornucopian worldview: namely that the earth’s bounty, adapted to our use
by human ingenuity, guarantees a perpetual growth in goods and services.
At the root of the cornucopian worldview lies a brand of technological
triumphalism, an unshakeable confidence in technological innovation to
solve all social and environmental problems, be it world hunger, climate
change, or declining oil reserves. In sustainability discourse, there is a wide
spectrum of opinion from the extremes of cornucopian optimism on one
side and to the doom-and-gloom scenarios that suggest it is already too late
to avert a new Dark Age of resource scarcity and chronic conflict on the
other.
—
ane .
| ‘A LILY
M4
California, the Cornucopia
of the World Cover of an
1885 promotional book
prepared by the California
Immigration Commission.
Source: The California State
Library
For every generation entering a Dark Age, there were parents who enjoyed
a better life, but who somehow failed to pass along their prosperity. No one
wants to fail their children in this way. To this extent, biology dictates
multigenerational thinking and ethics. Though it might not always be
obvious, we are all already the beneficiaries of multi-generational planning.
The world-leading American higher education system, for example,
depends upon an intergenerational structure and logic—a financial and
human investment in the future committed to by multiple generations of
Americans going back to the 19" century. But conversely, in terms of
vulnerability, just as higher education in the United States is neither
necessarily permanent nor universal, but a social institution built on an
unwritten contract between generations, so the lifestyle benefits of
advanced society as we know it will not simply perpetuate themselves
without strenuous efforts to place them on a sustainable footing.
Our current problem lies in the fact that multigenerational thinking is so
little rewarded. Our economic and political systems as they have evolved in
the Industrial Age reward a mono-generational mindset driven by short-
term profits and election cycles. In the West, for example, there is no
significant political philosophy, regulatory system, or body of law that
enshrines the idea that we act under obligation to future generations, despite
widely held views that we naturally must. One challenge of sustainability is
to channel our natural biological interest in the future into a new ethics and
politics based on multigenerational principles. Many indigenous
communities in the world, marginalized or destroyed by colonialism and
industrialization, have long recognized the importance of sustainability in
principles of governance, and provide inspiring models. The Great Law of
the Iroquois Confederacy, for example, states that all decisions made by its
elders should be considered in light of their impact seven generations into
the future.
To embrace an ethics of sustainability is to accept that our rapid
industrialization has placed us in the role of planetary managers,
responsible for the health, or ruinous decline, of many of the globe’s vital
ecosystems. This ethics requires we activate, in the popular sense, both
sides of our brain. That is, we must toggle between a rational consideration
of our environmental footprint and practical issues surrounding the
reinvention of our systems of resource management, and a more humble,
intuitive sense of our dependence and embeddness within the web of life.
Both reason and emotion come into play. Without emotion, there can be no
motivation for change. Likewise, without an intellectual foundation for
sustainability, our desire for change will be unfocused and ineffective. We
are capable of adapting to a complex world and reversing broad-based
ecosystem decline. But to do so will require technical knowledge wedded to
an ethical imagination. We need to extend to the natural world the same
moral sense we intuitively apply to the social world and our relations with
other people.
Sustainability ethics thus does not need to be invented from whole cloth. It
represents, in some sense, a natural extension of the ethical principles
dominant in the progressive political movements of the 20" century, which
emphasized the rights of historically disenfranchised communities, such as
women, African-Americans, and the global poor. Just as we have been
pressed to speak for dispossessed peoples who lack a political voice, so we
must learn the language of the nonhuman animal and organic world, of
“nature,” and to speak for it. Not simply for charity’s sake, or out of selfless
concern, but for our own sake as resource-dependent beings.
Remote Responsibilities
What distinguishes an ethics of sustainability from general ethical
principles is its emphasis on remote responsibilities, that is, our moral
obligation to consider the impact of our actions on people and places far
removed from us. This distance may be measured in both space and time.
First, in spatial terms, we, as consumers in the developed world, are
embedded in a global web of commerce, with an ethical responsibility
toward those who extract and manufacture the goods we buy, whether it be
a polo shirt from Indonesia, or rare metals in our computer extracted from
mines in Africa. The economic and media dimensions of our consumer
society do not emphasize these connections; in fact, it is in the interests of
“consumer confidence” (a major economic index) to downplay the
disparities in living standards between the markets of the developed world
and the manufacturing countries of the global south (Africa, Asia, Latin
America), which serve as the factories of the world.
Second, as for sustainability ethics considered in temporal terms, the moral
imagination required to understand our remote responsibilities poses an
even greater challenge. As we have seen, the landmark United Nations
Brundtland Report establishes an ethical contract between the living and
those yet to be born. For an industrial civilization founded on the no-limits
extraction of natural resources and on maximizing economic growth in the
short term, this is actually a profoundly difficult challenge to meet. More
than that, the practical ethical dilemmas it poses to us in the present are
complex. How, for instance, are we to balance the objectives of economic
development in poorer nations—the need to lift the world’s “bottom
billion” out of poverty—with the responsibility to conserve resources for
future generations, while at the same time making the difficult transition
from industrialized fossil fuels to a low-carbon global economy?
The issue of fairness with regard to individual nations’ carbon emissions
reduction mandates is a specific example of how ethical issues can
complicate, or even derail, negotiated treaties on environmental
sustainability, even when the parties agree on the end goal. In the view of
the developing countries of the global south, many of them once subject to
colonial regimes of the north, the advanced industrialized countries, such as
the United States and Europe, should bear a heavier burden in tackling
climate change through self-imposed restraints on carbon consumption.
They after all have been, over the last 200 years, the principal beneficiaries
of carbon-driven modernization, and thus the source of the bulk of
damaging emissions. For them now to require developing nations to curb
their own carbon-based modernization for the benefit of the global
community reeks of neo-colonial hypocrisy. Developing nations such as
India thus speak of common but differentiated responsibilities as the
ethical framework from which to justly share the burden of transition to a
low-carbon global economy.
From the point of view of the rich, industrialized nations, by contrast,
whatever the appearance of historical injustice in a carbon treaty, all nations
will suffer significant, even ruinous contractions of growth if an aggressive
mitigation agreement among all parties is not reached. Some commentators
in the West have further argued that the sheer scale and complexity of the
climate change problem means it cannot effectively be addressed through a
conventional rights-based and environmental justice approach. To this
degree at least, the sustainability issue distinguishes itself as different in
degree and kind from the landmark social progressive movements of the
20" century, such as women’s emancipation, civil rights, and
multiculturalism, to which it has often been compared.
Disputes over the complex set of tradeoffs between environmental
conservation and economic development have dominated environmental
policy and treaty discussions at the international level for the last half
century, and continue to stymie progress on issues such as climate change,
deforestation, and biofuels. These problems demonstrate that at the core of
sustainability ethics lies a classic tragedy of the commons, namely, the
intractable problem of persuading individuals, or individual nations, to take
specific responsibility for resources that have few or no national boundaries
(the atmosphere, the oceans), or which the global economy allows to be
extracted from faraway countries, the environmental costs of which are thus
“externalized” (food, fossil fuels, etc). How the international community
settles the problem of shared accountability for a rapidly depleting global
commons, and balances the competing objectives of economic development
and environmental sustainability, will to a large extent determine the degree
of decline of the planet’s natural capital this century. One tragic prospect
looms: If there is no international commitment, however patchwork, to
protect the global resource commons, then the gains in economic prosperity,
poverty alleviation and public health in the developing world so hard won
by international agencies over the second half of the 20" century, will
quickly be lost.
L WEAR TT
LACKS DINOGUR...
Tragedy of Commons The tragedy of the
commons is evident in many areas of our lives,
particularly in the environment. The over-fishing
of our oceans that causes some marine life to be in
danger of extinction is a good example. Source:
Food and Agriculture Organization of the United
Nations
Precautionary Principle
The precautionary principle is likewise central to sustainability ethics.
The margins of uncertainty are large across many fields of the biophysical
sciences. Simply put, there is a great deal we do not know about the specific
impacts of human activities on the natural resources of land, air, and water.
In general, however, though we might not have known where the specific
thresholds of resilience lie in a given system—say in the sardine population
of California’s coastal waters—the vulnerability of ecosystems to human
resource extraction is a constant lesson of environmental history. A
prosperous and vital economic engine, the Californian sardine fishery
collapsed suddenly in the 1940s due to overfishing. The precautionary
principle underlying sustainability dictates that in the face of high risk or
insufficient data, the priority should lie with ecosystem preservation rather
than on industrial development and market growth.
Great Fish Market by Jan Brueghel Though we might not have
known where the specific thresholds of resilience lie in a given system
—say in the sardine population of California’s coastal waters—the
vulnerability of ecosystems to human resource extraction isa constant
lesson of environmental history. Source: Public Domain
Sustainability, in instances such as these, is not a sexy concept. It’s a hard
sell. It is a philosophy of limits in a world governed by dreams of infinite
growth and possibility. Sustainability dictates that we are constrained by
earth’s resources as to the society and lifestyle we can have. On the other
hand, sustainability is a wonderful, inspiring concept, a quintessentially
human idea. The experience of our own limits need not be negative. In fact,
what more primitive and real encounter between ourselves and the world
than to feel our essential dependence on the biospheric elements that
surround us, that embeddedness with the air, the light, the warmth or chill
on our skins, and the stuff of earth we eat or buy to propel ourselves over
immense distances at speed unimaginable to the vast armies of humanity
who came before us.
Sustainability studies is driven by an ethics of the future. The word itself,
sustainability, points to proofs that can only be projected forward in time.
To be sustainable is, by definition, to be attentive to what is to come. So
sustainability requires imagination, but sustainability studies is also a
profoundly historical mode, committed toreconstruction of the long,
nonlinear evolutions of our dominant extractivist and instrumentalist views
of the natural world, and of the “mind-forg’d manacles” of usage and
ideology that continue to limit our ecological understanding and inhibit
mainstream acceptance of the sustainability imperative.
Sustainability studies thus assumes the complex character of its subject,
multiscalar in time and space, and dynamically agile and adaptive in its
modes. Sustainability teaches that the environment is not a sideshow, or a
scenic backdrop to our lives. A few more or less species. A beautiful
mountain range here or there. Our relation to our natural resources is the
key to our survival. That’s why it’s called “sustainability.” It’s the grounds
of possibility for everything else. Unsustainability, conversely, means
human possibilities and quality of life increasingly taken away from us and
the generations to come.
Review Questions
Exercise:
Problem:
What does it mean to say that global environmental problems such as
climate change and ocean acidification represent a “tragedy of the
commons?” How are global solutions to be tied to local transitions
toward a sustainable society?
Exercise:
Problem:
How does sustainability imply an “ethics of the future?” And in what
ways does sustainability ethics both borrow and diverge from the
principles that drove the major progressive social movements of the
20" century?
Glossary
common but differentiated responsibilities
An ethical framework, promoted particularly by developing nations,
that recognizes mitigation of global warming as a shared
responsibility, but at the same time argues that the wealthy,
industrialized countries of the West that have been the historical
beneficiaries of carbon-based development should accept a greater
burden for both reducing global carbon emissions, and providing
developing nations with the technology and economic means to
modernize in sustainable ways.
Cornucopian
The view that economic growth and technological innovation will
continue to improve the conditions of humanity as they have done for
the past 500 years, and that no environmental constraints are important
or permanent.
precautionary principle
The proposition that decision-making should be driven by a concern
for the avoidance of bad outcomes. In environmental terms, this means
coordinating economic development and the profit motive with the
need to maintain resilient ecosystems.
remote responsibilities
An ethical extension of systems literacy and the principle of
connectivity: we are linked to peoples and places remote from us
through the web of global industrial production and commerce, and
thus have responsibility toward them.
Sustainable Infrastructure - Chapter Introduction
In this chapter several important aspects of urban resiliency and
sustainability are presented, beginning with the concept of a sustainable
city, and proceeding through various elements of urban systems: buildings,
energy and climate action planning, transportation, and stormwater
management. The chapter concludes with a case study of a net zero energy
home, one in which perhaps you can envision yourself inhabiting one day.
Introduction
At present 80% of the US population lives in urban regions, a percentage
that has grown steadily over the past two hundred years. Urban
infrastructures have historically supported several needs of the population
served: the supply of goods, materials and services upon which we rely;
collection, treatment and disposal of waste products; adequate
transportation alternatives; access to power and communication grids; a
quality public education system; maintenance of a system of governance
that is responsive, efficient and fair; generation of sufficient financial and
social capital to maintain and renew the region; and insurance of the basic
elements of safety and public health. Collectively, these needs have been
perceived as the basic attributes needed to make an urban region livable.
Urban infrastructures are designed and built in response to social needs and
economies of scale that urbanization has brought about. Although our urban
infrastructures are in many ways remarkable achievements of engineering
design that were conceived and built during times of rapid urbanization, as
they have aged and, inevitably, deteriorated; significant strains on their
function and ability to provide services have become evident. In its program
to identify the “grand challenges” facing society in the near future, the
National Academy of Engineering has proposed several focus areas, among
them the restoration and improvement of urban infrastructures. Such a
challenge involves the need for renewal, but also presents opportunities for
re-envisioning the basis of infrastructure design and function as we move
forward. Urban infrastructures of the past were not generally conceived in
concert with evolutionary social and ecological processes. This has resulted
in several characteristic attributes: conceptual models of infrastructure that
perceive local ecological systems either indifferently or as obstacles to be
overcome rather than assets for harmonious designs; a general reliance on
centralized facilities; structures that often lack operational flexibility such
that alternative uses may be precluded during times of crisis; heavy use of
impervious and heat absorbing materials; systems that have become
increasingly costly to maintain and that are often excessively consumptive
of natural resources on a life cycle basis; and a built environment the
materials and components of which are often difficult to reuse or recycle.
The urban environment is an example of a complex human-natural system.
The resiliency of such systems lies in their capacity to maintain essential
organization and function in response to disturbances (of both long and
short duration). A complimentary view, inspired by traditional ecological
and economic thought focuses on the degree of damage a system can
withstand without exhibiting a “regime” shift, defined as a transition that
changes the structure and functioning of the system from one state to
another as a result of one or more independent factors. Upon exceeding a
given threshold, the system shifts to a new alternative state which may not
be readily reversed through manipulation of causative factors. In the context
of human-natural systems, regime shifts can have significant consequences,
and not all shifts are preferred by the human component of the system. To
the extent that change of some order is a given property of essentially all
dynamic systems, “preferred” resiliency might be viewed as the extent to
which human societies can adapt to such shifts with acceptable levels of
impacts. Resilient infrastructures, then, are those which most readily
facilitate such adaptation. Much of the foregoing discussion also applies to
sustainability, with the added constraints of the sustainability paradigm: the
equitable and responsible distribution of resources among humans, present
and future, in ways that do not harm, and ideally reinforce, the social and
biological systems upon which human society is based. Although there are
important differences between those two concepts, there remains a close
interrelationship that stems from the same need: to understand and design
urban infrastructural systems that enhance human interactions with the
environment.
It is beyond the scope of this book to present an exhaustive treatment of the
urban environment, indeed there are many books and treatises on this topic.
But in this chapter several important aspects of urban resiliency and
sustainability are presented, beginning with the concept of a sustainable
city, and proceeding through various elements of urban systems: buildings,
energy and climate action planning, transportation, and stormwater
management. The chapter concludes with a case study of a net zero energy
home, one in which perhaps you can envision yourself inhabiting one day.
Further Reading
Nancy B. Grimm, Stanley H. Faeth, Nancy E. Golubiewski, Charles L.
Redman, Jianguo Wu, Xuemei Bai, and John M. Briggs (2008). “Global
Change and the Ecology of Cities”, Science 8 February 2008: Vol. 319 no.
5864 pp. 756-760 DOI: 10.1126/science.1150195.
The Sustainable City
In this module, the following topics will be addressed: 1) a profile of the
sustainable city, 2) technology's influence on the form and pattern of the
sustainable city, 3) the connections between the design of our cities and
resource use, 4) sharing the earth’s bounty with all of the earth’s
inhabitants, 5) the alteration of one’s lifestyle in order to live more
sustainably.
Learning Objectives
After reading this module, students should be able to
e imagine what a sustainable city will look like and what it will mean to
live in one
e understand how technology will influence the form and pattern of the
sustainable city
e explore the connections between the design of our cities and resource
use
e recognize that sustainability means we will have to share the earth’s
bounty with all of the earth’s inhabitants
e think about how one’s lifestyle will have to be altered in order to live
more sustainably
The Sustainable City
Family Residence Bulldin ?
One car Compact — no unused Site compta
Sustainable Ethic rooms on
Uses Mass Transt | * aa (zero lao Energy & Almosphere
Recycles Generates & uses
Composis Materials & Resources
Mostly local
Non-toxic
Indoor Air Quality
Wired
Wired — Cyborgean
Sustainable Ethic
Safe & Secure Walkable Open Space & Recreation
Eyes & Ears on the Street Bike Friendly Community Gardens
Mass Transit Options
Community Area
Neighborhoods linked by various transit options Job & Commercial Centers Its Own diverse identity
Facilitates brownfield redev
Farmland Preservation Growth Management Cluster Development when new areas developed
Megalopolis
High Speed Rail links Preserves Natural Areas & Water Supply
Introduction
Sustainability, from science to philosophy to lifestyle, finds expression in
the way we shape our cities. Cities are not just a collection of structures, but
rather groups of people living different lifestyles together. When we ask if a
lifestyle is sustainable, we’re asking if it can endure. Some archaeologists
posit that environmental imbalance doomed many failed ancient
civilizations./{22™°te] What could the sustainable city look like, how would it
function, and how can we avoid an imbalance that will lead to the collapse
of our material civilization? This module will make some educated guesses
based upon the ideas and practices of some of today’s bold innovators.
Montgomery, David, Dirt, The Erosion of Civilizations, University of
California Press, 2007
Throughout history settlement patterns have been set by technology and
commerce. Civilizations have produced food, clothing and shelter, and
accessed foreign markets to purchase and sell goods. Workers traditionally
had to live near their place of occupation, although in modern industrial
times advanced transportation systems have enabled us to live quite a
distance from where we work.
In hindsight we can see how reliance on water and horse-drawn
transportation shaped historical civilizations and how this equation was
radically altered with the rise of the automobile following World War II.
While attempting to envision the “Sustainable City” we must discern what
factors will influence its shape and form in the future.
Energy
For the last century energy has been affordable and plentiful, limited mainly
by our technological ability to use it. Contemporary civilization consumes
474 exajoules (474x10!8 J=132,000 TWh). This is equivalent to an average
annual power consumption rate of 15 terawatts (1.504«10!3 w),|feotmote] The
potential for renewable energy is: solar energy 1,600 EJ (444,000 TWh),
wind power 600 EJ (167,000 Wh), geothermal energy 500 EJ (139,000
TWh), biomass 250 EJ (70,000 TWh), hydropower 50 EJ (14,000 TWh)
and ocean energy 1 EJ (280 TWh).!{2lmote] Even though it is possible to
meet all of our present energy needs with renewables, we do not do so
because the way in which the market prices our fossil reserves. In the
current framework, when a company exploits resources it normally does not
account for the loss of resource base or for environmental damage. Gasoline
has been cheap in the United States because its price does not reflect the
cost of smog, acid rain, and their subsequent effects on health and the
environment! ometel Jet alone recognize that the oil reserves are being
depleted. Scientists are working on fusion nuclear energy; if that puzzle is
solved energy will be affordable, plentiful and carbon neutral. See
Environmental and Resource Economics and Sustainable Energy Systems
for more detail.
Statistical Review of World Energy 2009, BP. July 31, 2006. Retrieved
2009-10-24.
State of the world 2009, Worldwatch institute, 2009
Hawken, Paul; ‘The Ecology_of Commerce,_a Declaration of Sustainability;
Harper Buisness, 1993, p.76
Materials & Waste
Scientists are producing materials not previously known to nature with
unpredictable effects on bio-systems. Some, such as dioxin, are highly
toxic; others (e.g. xenoestrogens - which act as endocrine disruptors) have
more subtle effects. In the future the government will likely continue to
expand its regulation of the production, use and disposal of chemicals. Even
heretofore benign processes, such as the production of garbage and
greenhouse gases, will probably need to be controlled as civilization
exceeds the capacity of natural systems to absorb and recycle our waste
products.
Recycling and composting will reduce waste streams and “material
exchanges” will take waste from one group and transfer it efficiently to
others, thus reducing trash volume. Chicago’s Rebuilding Exchange, for
instance, allows donors to take a tax deduction while it chargers buyers a
greatly reduced fee to reuse materials that would otherwise be sent to the
landfill. Although the Rebuilding Exchange is a physical location, similar
material exchanges could be virtual as they connect seller/donors to
buyers/users online. Old landfills might be mined as raw material use by a
larger developed world (the addition of Asia’s billions) creates demand
while technology drives down the cost of extraction. These modern
economic realities, along with the arrival of useful technology, represent the
rise of collaborative consumption.
Long before modern lighting and HVAC systems were developed, buildings
relied upon natural light and ventilation. With support from a growing body
of science supporting the public health benefits, contemporary designers are
rediscovering the role biophilia — the human affinity for nature — plays in
the spaces we occupy. When adjacent to residential areas, green spaces have
been shown to create neighborhoods with fewer violent and property crimes
and where neighbors tend to support and protect one another, ototel
Studies have shown that natural daylight increases commercial sales!2mote]
and green schools improve test scores!2omete] Biomimicry is also part of
the green revolution. The idea behind biomimicry is that nature has already
solved many of the challenges that face us. One example is the development
of new friction-free surfaces, modeled on the slippery skin of the Arabian
Peninsula's sandfish lizard, an advance that could eliminate the use of ball
bearings in many products as well as industrial diamond dust in automobile
air bags. The pearl oyster uses carbon dioxide to construct its calcium
carbonate shell, so a Canadian company developed a technology that
reduces large amounts of CO? in cement production. 300,000 buildings in
Europe use self-cleaning glass that mimics the way water balls up on lotus
leaves and simply rolls off.'!2°™2te! Tn the future, we should see more of a
return to natural systems as well as the use of new materials that mimic
nature in our sustainable city.
http://www. planning ,.org/cityparks/briefingpapers/saferneighborhoods.htm,
Accessed 4/29/11
http://www. greenbiz.com/sites/default/files/document/O16F8527.pdf,
accessed 4/30/11
http://www.usgbc.org/ShowFile.aspx?DocumentID=2908, accessed 4/30/11
dyn/content/article/2008/12/28/AR2008122801436.html, accessed 4/29/11
Social Equity
Perhaps the most significant development that separates sustainability from
its conservation antecedents is the element of social equity. The
environmental and conservation movements have been criticized in the past
for being too "white collar" and promoting the interests of the “haves”;
these movements have traditionally not dealt with the needs of the
underclass in the U.S. and, especially, developing countries. In Agenda 21,
the manifesto of the Earth Summit conference on the environment held in
Rio de Janeiro in 1992, sustainable development was viewed as the strategy
that would be needed to increase the basic standard of living of the world's
expanding population without unnecessarily depleting our finite natural
resources and further degrading the environment upon which we all depend.
[footnote] The challenge, as viewed at the Earth Summit, was posed in terms
of asking humanity to collectively step back from the brink of
environmental collapse and, at the same time, lift its poorest members up to
the level of basic human health and dignity.
Sitarz, Daniel, editor; 1993; AGENDA 21: The Earth Summit Strategy to
Save Our Planet; Earthpress; Boulder, Co; 1993; p.4
The concept of ecological footprint asks each of us to limit resource use to
our equitable share. Sitting on the apex of civilization the Western world is
being asked to share the earth’s bounty with the masses of Asia, South
America and Africa. If technology continues to advance we can do this
without significant long-term degradation of our standard of living. Short-
term economic dislocations are inevitable, however, as increasing demand
from China and India bring us to peak oil and rising transportation costs
will highlight the nexus between location efficiency and affordable housing.
The Center for Neighborhood Technology, for instance, has mapped 337
metropolitan areas covering 80% of the United States population showing
how efficient (near mass transit) locations reduce the cost of living (housing
+ utilities transportation) and vice versa. The reality of rising transportation
costs could have a significant impact on the shape of the city. Lookin target-
id="targetid"g backward we also realize that racial politics were one of the
dynamics that fueled suburban expansion in the 50’s and 60’s decimating
many of our urban centers. The Sustainable City of the future, if it works,
will have stably integrated mixed income neighborhoods.
Technology
Computers brought intelligence to the Machine Age and transformed it into
the Information Age. Markets run on information and better information
will help the markets perform more efficiently. Whereas in the past
surrogate Measures were developed to guess at impacts, information
technology can track actual use. For example, do we charge everyone the
same fee for water and sewers or do we measure their use, charge
proportionally, and thus encourage landowners to reduce their use? In
Miami the (congestion pricing) charge for driving in the special lanes goes
up instantaneously with actual traffic conditions. As the old adage goes,
“What gets measured gets managed,” and as technology increases the
precision to which environmental measures, consumption, and behavior
increases, our ability to manage, and therefore reduce negative impacts, will
increase.
In the past humans have been one of the beasts of burden and workers have
been needed to produce and move goods. Modern factories reduce human
labour needs and artificial intelligence will soon carry most of the load in
our partnership with machines. In the Information Age humans should no
longer have to live and work near the factories and centers of commerce
and jobs will move from the production of goods to the provision of
services. People may choose to live in exciting urban centers, but if one
wants a bucolic life style telework will offer an alternative.
Shrinking Cities
Many American cities have declined in population from highs immediately
following World War I, even as the host metropolitan area has continued to
grow. While populations have declined poverty and other social problems
have been concentrated. !f0™ote] Th the United States, nearly 5,000,000 acres
of vacant property (including brownfields) exist. This is equivalent to the
combined land area of the nation’s 60 largest cities.omote!
2005-2007 American Community Survey three-year estimates
Joe Dufficy, USEPA,
ufficy-Brooks%20Furio.pdf accessed 4/25/11
Some Shrinking Cities
[1950] 503,000 |
| 2008] 333,000] ___33.8%|
1960) 262,000)
| 2008)
Data ern U. 3. Cennus Bureau
The traditional planning approach has been to focus on managing growth
and new development through time-honored tools such as comprehensive
planning, zoning, subdivision regulations, and urban growth boundaries.
[footnote] This growth-oriented approach to addressing the shrinking city is
now criticized. '{2™0le] Some commentators postulate that green
infrastructure offers a better model for improving these cities health.!{o™ote!
Dawkins, Casey J., and Arthur C. Nelson. (2003). “State Growth
Management Programs and
Central City Revitalization.” Journal of the American Planning Association,
69(4), 381-
396.
Oswalt, Philipp. 2006. Shrinking Cities Volume 2: Interventions. Ostfildern,
Germany: Hatje
Cantz Verlag
Joseph Schilling, Blueprint Buffalo—Using Green Infrastructure to Reclaim
America’s Shrinking Cities,
http://metrostudies. berkeley.edu/pubs/proceedings/Shrinking/18Schilling P
A_final.pdf, accessed 4/25/11
How could these factors manifest themselves in our sustainable city? They
will influence its design and our settlement patterns will influence our
lifestyles. You are not only what you eat but also where you live. For
instance:
Transportation
Most agree that walkability is a key component of any sustainable
neighborhood. Walkability not only reduces energy use, but also increases
public health. How can we measure walkability? Walkscore.com identifies
and measures nearby amenities and provides a rating for specific locations
and neighborhoods. Try it for where you live.
Sustainable cities could consist of walkable neighborhoods that separate
pedestrian, bike and vehicular traffic and are connected to each other
through multiple transportation modes, with biking and mass transit choices
in addition to the automobile. Instead of averaging 10 (auto) trips per unit
per day!fcototel most residents would not use an automobile daily and
instead walk or bike or order online. Trip generation would be reduced
through telework and ecommerce. Goods would be brought to residents in
bulk delivery trucks using services like UPS, Fedex and Peapod. Under
telework many would only visit an office to attend meetings once or twice a
week (or less). Streets and intersections would be made less daunting to
pedestrians through traffic calming techniques.
based upon Institute of Traffic Engineers Trip Generation Manual, 1997
from http://www.maine.gov/mdot/planning-process-programs/trips.php
accessed 4/25/11
Walkable Neighborhood Picture shows a bike path in Chapinero,
Bogota. Source: Tequendamia (Own work) [CC-BY-SA-3.0] via
Wikimedia Commons
Most trips to other parts of the city would be made via mass transit. When
an individual car is need it would be provided through car sharing, or taxis.
Much to the dismay of science fiction fans, flying cars sound nice but it is
difficult to see how they can be sustainable until a non-polluting, renewable
energy source for air travel is obtained. Traffic congestion would be
relieved not through artificial subsidies (overbuilding roads and providing
free parking) but through congestion pricing, removal of free street parking,
and providing viable bicycle and mass transit alternatives.
Even rural centers could be planned as concentrated walkable
neighborhoods with viable transportation options. ‘Telework, e-commerce
and low impact cluster development would enable residents to enjoy
country living without a guilty conscience. Think in terms of a kibbutz
(collective farm) where most members do not own their own cars and rarely
have to use this type of transportation.
Cities will continue to draw entrepreneurs and foster productivity.!2omot!
Most of the population will reside in mega-regions and linking them
through high-speed rail that connects to mass transit will be the key to long-
term economic growth. |footnote]
Lincoln institute of Land Policy, April 26, 2100,
http://www.lincolninst.edu/news/atlincolnhouse.asp, accessed 4/27/11
quoting Edward Glaeser, author of "The Triumph of Cities,"
Lincoln institute of Land Policy, April 26, 2100,
http://www.lincolninst.edu/news/atlincolnhouse.asp, accessed 4/27/11
quoting Petra Todorovich, America 2050,
Water
Traditional approaches have sought to rapidly move stormwater away from
what we’ve built via gutters, sewers and artificial channels. While this
approach on the micro scale is intended to prevent local flooding and
undesired ponding, on the macro scale it may actually cause area wide
flooding. It also short-circuits the opportunity for water to naturally soak
into the ground — to water plants and recharge groundwater
resources|footnote] and, with traditional planting of lawns and other exotics,
necessitates bringing more water in for irrigation.
Conservation Design Forum from A Guide to Stormwater Best
Management Practices,
http://www.cdfinc.com/xm_client/client_documents/Chicago GuideTo Sto
rmwater_ BMPs.pdf, accessed 4/25/11
Best water management practices for sustainable cities would include:
e Green Roofs
¢ Downspouts, Rain Barrels and Cisterns
e Permeable Paving
e Natural Landscaping
e Filter Strips
Bioinfiltration using: Rain Gardens
e Drainage Swales
e Naturalized Detention Basins
© if
F |
| U, ! a |
re | b »
‘es }
| Tax
ul
aT
Green Roof The green roof of City Hall in Chicago, Illinois Source:
TonyTheTiger [CC-BY-SA-3.0] via Wikimedia Commons
These features are discussed in more detail in the Module Sustainable
Stormwater Management. The sustainable city would recharge its local
aquifer and surface water would flow primarily from groundwater and not
storm water discharge. Instead of charging a flat tax for storm and sanitary
sewer services, technology allows districts to charge usage fees based upon
volume, thus providing a financial incentive for sustainable design.
Governmental bodies could use these tools to encourage the reorientation
and designers could use the techniques outlined above as divert stormwater
into the ground rather than directly into surface water, |{20mote!
Newport, Robert, USEPA lecture to UPP 594 class 9/7/10
Working together, local government and project planners could also retrofit
older urban streets with attractive walkable streetscapes, just as Lansing,
Michigan has done as part of its combined sewer overflow project!!omote!
(below).
Newport, Robert, USEPA lecture to UPP 594 class 9/7/10
Some visionaries see even more dramatic transformations in the way we
deal with water. Sarah Dunn and Martin Felsen of Urbanlab envision
Chicago’s evolution into a model city for “growing water” by creating a
series of Eco-Boulevards that function as a giant Living Machine — treating
the city’s waste and storm water naturally, using micro-organisms, small
invertebrates such as snails, fish, and plants. Under their plan treated water
would be returned to the Great Lakes Basin and create a closed water loop
within Chicago, instead of being exported to the Mississippi and Gulf
Coast.
Food
The ancients would wonder at modern supermarkets with their food from
all over the world and fresh fruits and vegetables all year round. Yet most
environmental activists advocate locally produced organic food. Peak oil
will raise petrochemical costs and upset the dynamics of modern
agriculture, but it will be difficult to change the acquired tastes of the
consuming public.
USEPA is encouraging urban agriculture as one of the solutions to the
shrinking city.'{20motel Tt sees urban agriculture as not only providing a use
for vacant land, (thus addressing blight and the deleterious affect of neglect
on property values) but also as a potential cleanup strategy for
contamination. It addresses the problem of food deserts (lack of healthy,
affordable, fresh produce) in blighted inner city neighborhoods while
educating children and adults about farming and local enterprise.
Practitioners have found that urban farming enhances social capital and
community connections. Victory gardens produced about 40% of American
vegetables consumed during World War I[!!e™otel and urban gardens could
be a prime user of the compost that we could generate either through
individual compost bins or through collective efforts performed on a large
scale by our waste haulers.
http://www.epa.gov/brownfields/urbanag/index.html accessed 4/25/11
http://healthfreedoms.org/2011/03/10/food-crisis-triumph-part-2-victory-
gardens/ accessed 4/25/11
Urban Agriculture Some new crops being started, protected by shade
cloth barriers to the west. Note the new construction in the
background. This area used to be all public housing. The high rise
"warehouses of the poor" were torn down and are being replaced with
mix of market-rate and low-income housing (also called mixed income
housing.) The 1.5 acre parcel that City Farm sits on is owned by the
City of Chicago and provided, rent-free, to this non-profit initiative.
The property is valued at $8 million, however, so it's anyone's guess as
to when the city decides to terminate the agreement and City Farm
must move again. Source: Linda from Chicago, USA (New crops) [CC-
BY-2.0] via Wikimedia Commons
Many of us might belong to food cooperatives where the members contract
with organic farmers to purchase the food grown for them.!{2metel Tp
Sustainable Cities farming will not just be an interim land use in blighted
neighborhoods but, like Prairie Crossing in Grayslake, Illinois, will be an
integral part of the community plan. Some even forecast vertical farming in
the great cities of the world.
Buildings & Neighborhoods
Americans have come a long way from the pioneer one room log cabin and
crowded immigrant tenement. The average American house size has more
than doubled since the 1950s and now stands at 2,349 square feet, |{omote]
Sustainability will probably mean more efficient use of smaller homes, and
McMansions might become multi-family dwellings, putting pressure on
local ordinances and home association rules.!fomote]
Margot Adler, NPR, Behind the Ever-Expanding American Dream House,
http://www.npr.org/templates/story/story.php?storyId=5525283, accessed
4/25/11
Lincoln institute of Land Policy, April 26, 2100,
http://www.lincolninst.edu/news/atlincolnhouse.asp, accessed 4/27/11
quoting Arthur C. Chris Nelson, University of Utah
McMansions Home with large garage and short driveway depth
taking up a large amount of street frontage. Also evident: several
cheaply installed neoclassical elements, a brick facade, no side
windows, and poorly proportioned windows on the front. Source:
John Delano of Hammond, Indiana [CCQ] via Wikimedia
Commons
Second (& third) homes? The Joint Center for Housing Studies at Harvard
University showed a dramatic rise in vacation homes, from 3.1 million such
units in the 1990 Census to over 6 million in the Housing Vacancy Survey
ten years later, /!0mote] Tf we want to equitably share the world’s resources
with emerging markets we’ll have to figure out how to manage this desire
to spend time in more than one place in a more conservative manner. Time-
sharing addresses this need, as does the (still) growing hotel and vacation
resort industry.
Zhu Xiao Di, Nancy McArdle and George S. Masnick, Second Homes:
What, How Many, Where and Who, February 2001,
accessed 4/25/11
Homes use about 23% of all energy in the United States. '{20™ote! In the
future many of our homes will generate their own power (See Case Study:
A Net-Zero Energy Home in Urbana, Illinois). Today ultra-efficient
homes combine state-of-the-art, energy-efficient construction and
appliances with commercially available renewable energy systems, such as
solar water heating and solar electricity, so that the net energy use is zero or
even less than zero (positive energy production).!{2°™2te! There have been
efforts since the 70’s oil crisis to promote (mandatory) energy codes, but
voluntary efforts such as Energy Star and LEED are the ones that have
made substantial headway.
http://energyfuture.wikidot.com/us-energy-use, accessed 4/25/11
mytopic=10360, accessed 4/25/11
LEED!otnote] _ | eadership in Energy and Environmental Design, a
voluntary effort by the U.S. Green Building Council!©2™l] includes more
than energy and also gives points for site, water, materials and resources,
and indoor air quality. LEED in particular and sustainable construction in
general have found widespread acceptance as even the National Association
of Homebuilders has rolled out its own version of green
construction!2om2tel, Since its inception in 1998, the U.S. Green Building
Council has grown to encompass more than 10,000 projects in the United
States and 117 countries covering 8 billion square feet of construction space
and in April, 2011 LEED certified its 10,000" home in its LEED for Homes
program|footnote]’ The U.S government’s General Services Administration
(GSA), the part of the federal government that builds and manages federal
space, currently requires LEED Gold certification for all of its new
buildings (up from Silver).!{©2™otel Th addition to using fewer resources
sustainable buildings reduce absenteeism, improve employee morale, and
lead to improved educational performance. !0™ote!
http://www.usgbc.org/DisplayPage.aspx?>CategoryID=19, accessed 4/28/11
http://www.usgbc.org/, accessed 4/28/11
http://www.usgbc.org/Docs/News/LEED%20for%20Homes%2010k%20mil
estone April%202011.pdf, accessed 4/28/11
http://www. gsa. gov/portal/content/104462, accessed 4/28/11
See
tPerformanceSchools FINAL 1.sflb.ashx, accessed 4/20/11
In the Pacific Northwest the International Living Future Institute has set up
a Living Building Challenge to go beyond LEED and design and build
triple net zero (storm water, energy, wastewater) structures. As of Fall 2010
there were 70 registered projects!{2omote!
http://ilbi.org/about/About-Docs/news-documents/pdfs/world2019s-first-
living-building-certified-projects-unveiled, accessed 4/28/11
What about the neighborhoods where we live and raise our families? Many
now recognize that our grandparents' mixed-use, walkable neighborhoods
were more sustainable than today’s reality. The Congress for New
Urbanism!{22mete] promotes mixed use in contrast to its predecessor,
Congrés International d'Architecture Moderne (CIAM), which promoted
separation of use. CIAM, active in the first part of the 20th century,
proposed that the social problems faced by cities could be resolved by strict
functional segregation, and the distribution of the population into tall
apartment blocks at widely spaced intervals.!2°2™te] This view found its
expression in Le Corbusier’s The Radiant City (1935). Separation of Use
heavily influenced subdivision and building codes that, in turn, shaped Post
World War IT suburban expansion. In our suburbs zoning dictates mutually
exclusive uses in each district so that Industrial use is exclusive of
commercial, which is exclusive of residential. In the suburbs separation of
use combined with the platting of superblocks to replace the traditional grid
network gives us a lifestyle that produces 10 auto trips per unit per day,
because you need one car per driver to get around where much of America
lives.
http://www.cnu.org/
http://en. wikipedia.org/wiki/Congr%C3%A8s_ International d'Architecture
Moderne
CIAM’s view also formed the intellectual underpinning for large-scale
high-rise public housing projects. Today we recognize that safe, sound and
sanitary housing is not just indoor plumbing and more bedrooms, and that
affordable housing is not just rent but includes utility and transportation
costs and the right to live in a safe, mixed income, stably integrated
neighborhood. Our sustainable city should stand upon the leg of social
equity and include ethnic and income diversity. Neighborhoods should be
sited at efficient locations'22™°"! with broad transportation choices. What
will they look like? Most new urbanists think they will be similar to the
diverse neighborhoods built at the turn of the last century. Other visionaries,
such as Moshe Safdie, think it possible to integrate the variety and diversity
of scattered private homes with the economics and density of a modern
apartment building. Modular, interlocking concrete forms in Safdie’s Expo
67 defined the space. The project was designed to create affordable
housing with close but private quarters, each equipped with a garden. In a
different vein, in outlying Grayslake, Illinois, cluster development that
incorporates open space, wetlands, and a working organic farm enables
residents to live (somewhat) sustainably in the country. Our future must
recognize that we don’t want everyone to live in Manhattan or Brooklyn,
and we must provide for diverse tastes and lifestyles.
Will everything look futuristic, like the sets of Blade Runner or Star Wars?
Historic Buildings not only have a special charm but they represent a great
deal of embodied energy that is wasted if they are demolished. The
government and marketplace will probably continue to promote historic
rehab, including adaptive reuse where new uses are found for old buildings
through rehab that installs modern utilities and fixtures while preserving the
outer shell’s look and feel. In Chicago the Sears Powerhouse was converted
to a charter school and in Philadelphia Urban Outfitters took the old Navy
Yard and transformed it into a new corporate headquarters. In all five of the
former Navy Yard buildings, employees work in light-filled interiors with
open layouts. Most of the furnishings are custom-made and contain
recycled material (tabletops crafted from salvaged wood, for instance).
Amenities such as a gym, yoga studio, dog park, and farmers’ market
further add to the lively and informal atmosphere.
All of these gestures to what the CEO calls “a quality of life thing” help
Urban Outfitters boost employee satisfaction. Since moving into the new
headquarters, employee turnover has dropped to 11 percent, and fewer sick
days are being used. “They feel more linked to the community and culture
of the company.” The campus has improved his company’s ability to attract
new talent. The informal atmosphere is alluring to Millennial-aged
employees, who tend to value open, flexible work arrangements more than
previous generations of workers. “The campus has improved creative
collaboration, which ultimately impacts our bottom line,’ footnote]
Accessed 4/29/11
Work and Commuting
In the past we had to live near the places where we built things and
conducted our business. The factories of the industrial revolution demanded
labor, and packed the exploited workforce in nearby tenement housing.
Today intelligent machines perform most of the work in manufacturing our
goods and moving them from place to place. In the Information Age most
tasks can be performed anywhere within reach of the World Wide Web. In
Understanding Media Marshall McLuhan showed how “improved roads
and transport have reversed the ancient pattern and made cities the centers
of work and the country the place of leisure and of recreation. !{0™0te!” The
new reality once again reverses roles by locating the factories on vast
campuses away from the people and, the city becomes a place to meet, be
entertained and educated. Sustainable Cities of the future will probably still
function as the center for service industries such as health and beauty care,
hospitality, tourism, travel, and government, and other service industries,
such as insurance, advertising and marketing, and financial services, are
amenable to telework. Sure, we can eat our frozen dinners and get TV or on
line entertainment at home, but it’s still enjoyable to go out to eat and catch
a live show, concert, sporting event or movie. We get a better view of the
players on television, but the excitement of thousands of fans under one
roof is palpable. Many of us in the postindustrial Information Age will
not have to live near our factories, power plants or transportation centers,
because we just have to connect to the World Wide Web. In the Information
Age many of us might never have to attend physical meetings, but those of
us who do might find ourselves going to the office only a few times a
month. But it is important for those who tout cities as more sustainable
places to live (i.e. Cities pollute less per capita!!22™2te!) to understand that
rural areas can be just as benign as cities if one has the will and controls
resource use with the appropriate life style. Communal farms, for example,
generally have small ecological footprints, producing more resources than
they consume.
McLuhan, Marshall, Understanding Media, McGraw Hill, NY, 1964, p. 38
Hoornweg D., Sugar L., Lorena Trejos Gomez C., “Cities and greenhouse
gas emissions: moving forward,” 2011,
ct?patientinform-links=yes&legid=speau;0956247810392270v1 accessed
4/25/11
Telecommuting Source: Gilangreffi
(Own work) [GCO] via Wikimedia
Commons
Power
Today huge plants generate electricity from coal (44.9%), natural gas
(23.8%), atomic energy (19.6%), hydroelectric (6.2%), and other renewable
(e.g. wind, solar) (4%) sources. !fomote] Power affects urban form in that
urban centers must be connected to the grid, and the ubiquitous power line
tethers us to the power plant. Sustainable cities will probably not lose the
grid, but should accommodate those who want to produce their own power
by running the meter backwards. Until and unless atomic fusion supplies
cheap, safe, reliable power, renewables will compete with fossil fuels. Even
as we hit peak oil, coal will be plentiful for the foreseeable future. Coal will
continue to be cheap because its price will probably not reflect all the costs
of smog, acid rain, and its subsequent effects on health and the environment
[footnote] Jet alone recognize that the reserves are being depleted. As the
technology evolves and as government policy requires utilities to buy
power from small decentralized sources we will all get used to wind mills
and photovoltaic arrays. Geothermal heat pumps will heat and cool space
more efficiently. Zoning and building codes will have to be revised to deal
with solar access rights, noise from windmills and odors from biomass and
biofuels.
US Energy Information Administration, Net Generation by Energy
Source: Total (All Sectors), 1996 through December 2010,
Hawken; op cit p.76
Windmills Source: James McCauley from Enon, OH, United States of
America (Flickr) [C 0], via
Local wind generator, Spain, 2010
Source: By Patrick Charpiat (Own work)
[CC-BY-SA-3.0] via Wikimedia Commons
Technology will also enable us to operate more efficiently. One of the
problems with conventional power generation is that the plants must be
(over)sized to accommodate peak loads. In the future the “Smart Grid”
should smooth peak loads by instructing consumer appliances to perform
tasks, such as laundry and dishwashing, in low demand periods (middle of
the night), and will offer lower rates as an incentive.!omote]
See Section 2.7.2 & also CNT http://www.cnt.org/news/media/brockway-
consumerperspective.pdf, accessed 4/25/11
Microgrids A local microgrid in Sendai, Japan Source:
See page for author [Public domain], via Wikimedia
Commons
Commerce
Our parents and grandparents have seen dramatic change in the area of
commerce. Until 1950 we walked to the neighborhood store and most of the
goods we bought were produced locally. On special occasions you’d take
the trolley downtown to the central business district (CBD) to visit the large
department stores (e.g. Marshall Fields in Chicago, Macy’s in New York).
With the suburbanization following World War II CBD’s were replaced by
suburban malls. We drove to the malls. The CBD’s died out. For the last
thirty years big box chains have dominated retail, but most recently
ecommerce entices consumers with better selection and prices (and
sometimes no sales tax). Most of us find that we shop online more
efficiently and those that need the personal attention that retail
establishments currently offer might find that they will have to engage the
services of a personal shopper (note the shift from good to service). Most of
the goods we purchase, even food, have been produced somewhere else.
World trade, as measured in US dollars at current prices, has grown
astronomically, from $10.1 billion in 1900422"! to $62 billion in 1950, to
$15.2 trillion in 2010. US imports and exports have risen from $1.4 billion
(exports) in 1900 to $9.6/10.3 billion in 1950 and to $1.97/1.28 trillion in
2010, [footnote]
United Nations, INTERNATIONAL TRADE STATISTICS 1900 — 1960,
http://unstats.un.org/unsd/trade/imts/Historical%20data%201900-1960.pdf,
accessed 4/26/11
extracted from world Trade Organization database 4/26/11,
http://stat.wto.org/StatisticalProgram/WSDB ViewData.aspx?Language=E
In our Sustainable City of the Future ecommerce will probably rule, which
will mean a reduction in actual physical commercial floor area. When we
feel we need to see something in person we will visit centralized
showrooms, and pay for that service, but most purchases will be made on
line and the product delivered either by company delivery vehicles (e.g.
Peapod) or through common carriers (e.g. UPS, Fedex). New uses will be
found for dead malls.!!2°™°te! Neighborhood stores will fare better in
walkable neighborhoods, especially those that offer services in place of or
in addition to goods.
http://www.deadmalls.com/, accessed 4/26/11
It is unreasonable for us to expect to obtain all of our goods locally, but
regional specialization in the production of goods will reflect climate,
access to raw materials and markets, and locally developed expertise rather
than cheap labor and the ability to avoid environmental and workplace
safety regulations. Modern robots do not have to follow repetitive assembly
line logic of repeated application of the same exact set of instructions. They
can be programmed to intelligently consider each individual product and
thus can produce a wider variety of products, and many products will be
special ordered to fit individual tastes. Once we even out the playing field
(of necessary government regulation to deal with the externalities of
production) the cost of shipping should work towards more local
production. Goods will be made “just in time”!2™°! thus reducing
inventories and overproduction that is sent to landfills. Efficiency will be a
big part of the Sustainable City.
Planned obsolescence and its impact upon material culture is more
problematic. Fashion defies logic but speaks to the most basic instincts of
human behavior. How do we avoid the need for more closet space, let alone
offsite storage? New materials will enable us to change the look and feel of
clothing. Advances in crystal technology, for example, will allow us to
change its color and/or pattern.!!2°™°le] [Interlocking parts using material
similar to Velcro could let us change lapels, sleeves and other components
of garments, much as we now add or subtract liners for warmth. More
complicated goods will be designed for disassembly and recycling, o™o!
or replacement of key parts while keeping most of the old components.
Retrofit can add life to old buildings and machines, if we learn to view old
and retro as cool and in.
http://blog .cleveland.com/business/2007/12/clothes change colors with al
p.html, accessed 4/29/11
Sustainable Design - Not Just for Architecture Any More,
http://www.ece.ucsb.edu/~roy/classnotes/eddw/report_ SolidWorks design.p
df, accessed 4/26/11
A good example of how we can move towards sustainability is provided by
Interface, which repositioned their carpeting business from the sale of
goods to the leasing of floor covering services. Under the old paradigm the
consumer purchased a new carpet a few years after the old one began to
show wear. The selection was based upon the perception that the carpet
would last (e.g. because it felt thicker), but the reality was that the carpet
manufacturer made out better when new carpets had to be repurchased more
frequently. Under the new leasing paradigm the manufacturer owns the
carpet and therefore it is in their best interest to have it last longer.
Interface’s Solenium lasts four times longer and uses 40% less material than
ordinary carpets, an 86% reduction in materials intensity. When marketed as
floor covering services under its Evergreen Lease, modular floor tiles are
replaced as soon as they show any wear and, since 80% of wear takes place
on 20% of the area, this reduces material intensity by another 80%. In other
words, 3%of the materials are used under the new paradigm (yes, a 97%
reduction) than the old one. And the worn out panels are recycled, and no
chlorine or other toxic materials are used in its manufacture. !fomotel
Lovins, Lovins, and Hawken, A Road Map to Natural Capitalism, 1999,
Harvard Business REview
Education
Our children will find their place in tomorrow’s workplace based upon their
brains, not brawn. Education is the most important component in preparing
for tomorrow’s workplace. Classrooms today link via television and the
internet to amazing resources. More importantly, artificial intelligence has
the capacity to treat each student as an individual and to tailor instruction to
meet his or her individual abilities and needs, in contrast to the classroom
that moves, at best, at the speed of the average student.
E-Learning A ubiquitous-learning(u-learning) classroom where
students use electronic textbooks in the form of tablet PCs. Source: By
B.C. (Own work) [CC-BY-3.0] via Wikimedia Commons
The sustainable school should still contain classrooms, but it will probably
be supplemented by individualized computer learning labs. Each student
would have their own personal computer (see Cyborgean Man below) that
would link them to the internet. Classrooms would have multi-media
capabilities that would link to other classrooms around the world. Webinars
would make expert instruction available to all. As noted earlier, the
biophilia of green classrooms would improve learning and test scores.
Cyborgean Man & Big Brother
In his book “Understanding Media — The Extensions of Man” Marshall
McLuhan explains how once man creates an extension of himself, let’s say
writing, he both gains (the ability to remember more in his records) and
loses (not being able to remember as much without these written records)
abilities. {22™te] Horse drawn carriages and automobiles enable man to
travel faster and further even as his body gains weight and loses muscle
tone. Tents, tepees and igloos enable man to migrate from the primordial
forestlfootnotel to inhospitable climates, but man, like the tortoise, must lug
this shell of material civilization around with him.
McLuhan, Marshall, Understanding Media; The Extensions of Man,
McGraw Hill, NY, 1964
Paradise lost — the Hebrew word for forest is Pardais - paradise
Miniaturization in the Computer Age now promises to let us reinternalize
some of the external abilities we’ve created. Over ten years ago Thad
Starner, a research assistant at MITs media lab, garnered a lot of publicity
by calling himself a cyborg because he incorporated his computer monitor
into his glasses, and let his keyboard and computer hang as appendages by
his side, !feotmote] Today half the civilized world has smartphones that link us
via the Facebook, the World Wide Web, texts and tweets. In our sustainable
city we could all be wired, possibly though implants directly into out
brainstem. Artificial intelligence could provide a virtual butler that would
be available to schedule and keep track of our appointments, order our
groceries and other items, and help us with things we can’t even imagine
today. Advertising would be directed at us individually, as in Philip Dick’s
Minority Report! !omote] a5 advertisers use software like doubleclick!om™ot!
and links to national databases (see Big Brother below) to track who we are
and our buying preferences. This should be good for sustainability, as there
will be no need to hoard things for possible future use, and to discard them
when we no longer need them. Government would find it easier to poll
citizen’s preferences and opinions.
CNN at http://articles.cnn.com/1998-07-
s=PM:TECH, accessed 4/27/11
As in Philip Dick’s Minority Report, published in Fantastic Universe,
January 1956,
http://www. google.com/doubleclick/, accessed 4/27/11
Cyborgean Man Source: PIX-JOCKEY (Roberto
Rizzato)
http://www. flickr.com/photos/rizzato/234295 9844
/
In George Orwell’s 1984 everyone is constantly reminded, “Big Brother is
watching you.”!{0lmote] Th our sustainable city everyone will be watching
everyone else. Video surveillance webcams might be everywhere, and
everyone would have access to them. Everyone could have a reality show in
which those wanting to follow you would merely tune into the appropriate
URL and be able to choose the cameras and microphones that are in range.
Some people would not even turn off the feeds, ever. Artificial intelligence
(or actual humans for the more popular content) could provide edited
condensed feeds. Crime would go down in those areas with eyes and ears,
but crime will evolve and persist. It will be easy to research everyone you
meet and to stay connected. Since this will be by and large electronic it will
promote a sustainable lifestyle by not consuming additional resources.
Orwell, George (1949). Nineteen Eighty-Four. A novel. London: Secker &
Warburg
Review Questions
Exercise:
Problem:
Select an aspect of your day-to-day existence that has environmental
consequences. Describe the environmental consequences, and briefly
discuss more sustainable alternatives.
Exercise:
Problem:
What does a complete street look like? How does it differ from the
street outside of your home?
Exercise:
Problem:
Describe a sustainable neighborhood that you’re familiar with and
explain what makes it sustainable.
Exercise:
Problem:
If sustainability is so beneficial why isn’t everything sustainable?
Name one market barrier to sustainability and explain what can be
done to overcome it.
Glossary
biomimicry
Biomimicry or biomimetics is the examination of nature, its models,
systems, processes, and elements to emulate or take inspiration from in
order to solve human problems. The terms biomimicry and
biomimetics come from the Greek words bios, meaning life, and
mimesis, meaning to imitate. Examples include adhesive glue from
mussels, solar cells made like leaves, fabric that emulates shark skin,
harvesting water from fog like a beetle, etc.
e-commerce
Electronic commerce, commonly known as e-commerce, eCommerce
or e-comm, refers to the entire online process of developing,
marketing, selling, delivering, servicing and paying for products and
services.
ecological footprint
Ecological footprint is a measure of human demand on the Earth's
ecosystems. It is a standardized measure of demand for natural capital
that may be contrasted with the planet’s ecological capacity to
regenerate. It represents the amount of biologically productive land
and sea area necessary to supply the resources a human population
consumes, and to mitigate associated waste. Using this assessment, it
is possible to estimate how much of the Earth (or how many planet
Earths) it would take to support humanity if everybody followed a
given lifestyle.
low impact cluster development
Low impact cluster development is the grouping of buildings on a
portion of the site and devoting the undeveloped land to open space,
recreation or agriculture. Though cluster development lowers
development cost through savings on roads and infrastructure (sewers,
electric and water lines, etc.), it has issues such as conflicts with many
older zoning ordinances, perceptions of personal space (lower
individual lot size) and maintenance of common areas.
McMansion
A slang term that describes a large, opulent house that may be generic
in style and represents a good value for a homebuyer in terms of its
size. This type of home is built to provide middle and/or upper middle
class homeowners with the luxurious housing experience that was
previously only available to high-net-worth individuals.
postindustrial information age
Is a way of capturing the nature of western economies, in which most
people are no longer engaged in the production of goods (which is
highly automated) but rather deal with the publication, consumption,
and manipulation of information, especially by computers and
computer networks. A post-industrial society has five primary
characteristics: the domination of service, rather than manufacturing,
the pre-eminence of the professional and technical classes, the central
place of theoretical knowledge as a source of innovations, the
dominating influence of technology, and levels of urbanization higher
than anywhere else in the world.
telework
Working from a remote location, usually a home office, by
electronically linking to a company.
walkability
Walkability is a measure of how friendly an area is to walking.
Walkability has many health, environmental, and economic benefits.
Factors influencing walkability include the presence or absence and
quality of footpaths, sidewalks or other pedestrian right-of-ways,
traffic and road conditions, land use patterns, building accessibility,
destination density and safety, among others. Walkability is an
important concept in sustainable urban design.
Sustainability and Buildings
In this module, various ways buildings affect the environment and the characteristics of sustainable buildings are
discussed.
Learning Objectives
After reading this module, students should be able to
¢ understand the various ways buildings affect the environment
e describe the characteristics of sustainable buildings
Introduction
Buildings present a challenge and an opportunity for sustainable development. According to the most recent
available Annual Energy Outlook from the U.S. Environmental Information Administration, buildings account for
about 39% of the carbon dioxide emissions, 40% of primary energy use, and 72% of the electricity consumption in
the U.S. Additional information from the U.S. Geological Survey indicates that 14% of the potable water
consumption occurs in buildings.
Globally, buildings are the largest contributors to carbon dioxide emissions, above transportation and then industry.
The construction of buildings requires many materials that are mined, grown, or produced and then transported to
the building site. Buildings require infrastructure including roads, utility lines, water and sewer systems. People
need to be able to get to and from buildings to work, live, or take advantage of the services provided within them.
They need to provide a safe and comfortable environment for the people that inhabit them.
Aspects of Built Environmental
Environment Consumption Effects Ultimate Effects
Siting Energy Waste Harm to human health
Design Water Air pollution Soul
degradation
Construction Materials GHG emissions Loss of resources
Operation Natural Water pollution
resources
Maintenance Indoor pollution
Renovation Heat islands
Deconstruction Stormwater runoff
Noise
Impacts of the Built Environment Source: U.S. Environmental Protection Agency
http:/Avww.epa.gov/greenbuilding/pubs/about. htm
It is possible to design and construct fully functional buildings that have far fewer negative environmental impacts
than current norms allow. Beyond benefitting the environment, green buildings provide economic benefits
including reduced operating costs, expanded markets for green products and services, improved building occupant
productivity, and optimized life-cycle performance. Green buildings also offer social benefits that range from
protecting occupant comfort and health, to better aesthetic qualities, less strain on local infrastructure, and overall
improvement in quality of life.
In 1994, a group of experts was brought together by the National Renewable Energy Laboratory (NREL) to
develop a pathway and specific principles for sustainable development. According to these principles, building
should be:
¢ Ecologically Responsive: The design of human habitat shall recognize that all resources are limited, and will
respond to the patterns of natural ecology. Land plans and building designs will include only those with the
least disruptive impact upon the natural ecology of the earth. Density must be most intense near neighborhood
centers where facilities are most accessible.
¢ Healthy, Sensible Buildings: The design of human habitat must create a living environment that will be
healthy for all its occupants. Buildings should be of appropriate human scale in a non-sterile, aesthetically
pleasing environment. Building design must respond to toxicity of materials, care with EMF, lighting
efficiency and quality, comfort requirements and resource efficiency. Buildings should be organic, integrate
art, natural materials, sunlight, green plants, energy efficiency, low noise levels and water. They should not
cost more than current conventional buildings.
¢ Socially Just: Habitats shall be equally accessible across economic classes.
e Culturally Creative: Habitats will allow ethnic groups to maintain individual cultural identities and
neighborhoods while integrating into the larger community. All population groups shall have access to art,
theater and music.
¢ Beautiful: Beauty in a habitat environment is necessary for the soul development of human beings. It is yeast
for the ferment of individual creativity. Intimacy with the beauty and numinous mystery of nature must be
available to enliven our sense of the sacred.
e Physically and Economically Accessible: All sites within the habitat shall be accessible and rich in
resources to those living within walkable (or wheelchair-able) distance.
¢ Evolutionary: Habitats' design shall include continuous re-evaluation of premises and values, shall be
demographically responsive and flexible to change over time to support future user needs. Initial designs
should reflect our society's heterogeneity and have a feedback system.
What is meant by a sustainable or green building? The U.S. EPA defines green building as “the practice of creating
structures and using processes that are environmentally responsible and resource-efficient throughout a building's
life-cycle from siting to design, construction, operation, maintenance, renovation and deconstruction. This practice
expands and complements the classical building design concerns of economy, utility, durability, and comfort.”
(U.S. Environmental Protection Agency, 2010)
The benefits of sustainable buildings have already been documented. These buildings can reduce energy use by 24-
50%, carbon dioxide emissions by 33-39%, water use by 40%, and solid waste by 70% (Turmer & Frankel, 2008;
and more productive than their counterparts in other buildings, and this is important because in the U.S, people
spend an average of 90% or more of their time indoors (U.S. Environmental Protection Agency, 1987). Green
buildings tend to have improved indoor air quality and lighting.
There are also numerous perceived business benefits to green buildings, including decreased operating costs and
increased building value, return on investment, occupancy ratio, and rent ratio.
Materials and Methods of Construction
It is frequently stated that the most sustainable building is the one that is not built. This does not mean that we
should not have buildings, but rather that we should make the most of our existing buildings. Those buildings
already have the infrastructure and have utilized many materials for their construction.
A great deal of energy goes into making building materials. By volume, the major materials used within the U.S.
construction industry are crushed rock, gravel, sand, cement, cement concrete, asphalt concrete, timber products,
clay brick, concrete block, drywall, roofing materials, steel, aluminum, copper and other metals, plastics, paper,
paints, glues, and other chemical products. The building industry has been the largest consumer of materials in the
US for nearly 100 years (Horvath, 2004).
The manufacturing of cement, for instance, is an enormous producer of greenhouse gas emissions. Cement is made
of about 85% lime by mass, which is mixed with other ingredients such as shale, clay, and slate. It is formed into
an inorganic adhesive by heating the ingredients to a temperature of 1450 °C (2640 °F), and then grinding the
product into a powder. Cement comprises about 15% of concrete, which is made by mixing cement with sand,
small rocks, and water. Because it requires so much energy, the manufacture of cement is estimated to account for
as much as 5% of global anthropogenic greenhouse gas emissions (Humphreys & Mahasenan, 2002).
Construction of buildings is also related to deforestation. Our consumption of wood to build buildings and
furniture over the centuries has resulted in the clearing of many old-world forests and tropical forests. Trees are
harvested not only for fuel but also for construction material and to clear land for construction.
The demolition of old buildings to make way for new and construction projects themselves generate huge amounts
of waste. Careful deconstruction of buildings allows for reuse of materials in future construction projects or for
recycling of materials into new building (and other) products. Deconstruction creates economic advantages by
lower building removal costs due to value of materials and avoided disposal costs, reduces impact to site on soil
and vegetation, conserves landfill space, and creates jobs due to the labor-intensity of the process.
A 1998 EPA study of building-related construction and demolition (C&D) debris generation in the U.S. found that
an estimated 136 million tons of building-related C&D debris were generated in 1996, the equivalent to 2.8 pounds
per person per day. 43% of the waste (58 million tons per year) was generated from residential sources and 57%
(78 million tons per year) was from nonresidential sources. Building demolitions accounted for 48% of the waste
stream, or 65 million tons per year; renovations accounted for 44%, or 60 million tons per year; and 8 percent, or
11 million tons per year, was generated at construction sites.
Even when deconstruction is not possible, the waste can be recycled by sorting the materials after they are
collected and taken to a waste transfer station. Since new construction and renovation requires the input of many
materials, this is an opportunity to utilize products that enhance the sustainability of the building. These products
may be made of recycled content, sustainably grown and harvested wood and pulp materials, products that have
low emissions, and products that are sourced locally. These products enhance the sustainability of the building by
supporting local economies and reducing the fuel needed to transport them long distances.
Energy-saving Building Features
Energy efficient measures have been around a long time and are known to reduce the use of energy in residential
and commercial properties. Improvements have been made in all of these areas and are great opportunities for
further innovation. Green buildings incorporate these features to reduce the demand for heating and cooling.
Insulation
The building should be well insulated and sealed so that the conditioned air doesn’t escape to the outside.
Insulation can be installed in floors, walls, attics and/or roofs. It helps to have more even temperature distribution
and increased comfort as well.
High-performance Windows
Several factors are important to the performance of a window (see Figure A High-performance Window):
e Thermal windows are at least double-paned and vacuum-filled with inert gas. This gas provides insulation
e Improved framing materials, weather stripping and warm edge spacers reduce heat gain and loss
e Low-E coating block solar heat gain in the summer and reflect radiant heat indoors during the winter
Sealing of Holes and Cracks
Sealing holes and cracks in a building’s envelope as well as the heating and cooling duct systems can reduce
drafts, moisture, dust, pollen, and noise. In addition, it improves comfort and indoor air quality at the same time it
saves energy and reduces utility and maintenance costs.
Multiple Panes
Low-E Coating
Gas Fill
Warm Edge Spacers
Improved Frame Materials
A High-performance Window Source:
http://www.energystar.gov/ia/new_homes/features/Windows_062906.pd
Heating Ventilation and Air-conditioning (HVAC)
A large part of the energy consumption and thus environmental impact of a building is the building heating,
ventilation and air-conditioning (HVAC) systems that are used to provide comfortable temperature, humidity and
air supply levels. Buildings must be designed to meet local energy code requirements, but these are often not as
aggressive targets as they could be to demand more energy efficiency. In the U.S. ENERGY Star provides
guidance and benchmarking to help set more aggressive goals.
There are many ways HVAC systems can be designed to be more efficient. Variable air volume (VAV) systems
increase air flow to meet the increase or decrease in heat gains or losses within the area served. Having fans power
down when not needed saves energy, as does reducing the amount of air that needs to be conditioned and also
reduces the need for reheat systems. These systems are used to warm up an area if the cooled air supply is making
an area too cold. VAV systems can generally handle this by reducing air supply. All of this does need to be
balanced by making sure there is enough fresh air supply to meet the needs of the number of occupants in a
building. Otherwise, it will feel stuffy due to lack of air flow and oxygen.
Also using automated controls, whether it is a programmable thermostat in your home or a building automation
system (BAS) that uses computers to control HVAC settings based on schedules and occupancy, can significantly
reduce energy consumption.
The equipment itself can be made more energy efficient. For instance new home furnaces range in efficiency from
68-97%. Ideally, the most energy efficient furnace would be installed in a new home (U.S. Department of Energy,
2011).
Passive Solar Design
This type of architectural design does not require mechanical heating and cooling of a building. Instead it uses
heating and cooling strategies that have been used historically such as natural ventilation, solar heat gain, solar
shading and efficient insulation. Figure Passive Solar Design shows some of these elements. In the winter solar
radiation is trapped by the greenhouse effect of south facing windows (north in the southern hemisphere) exposed
to full sun. Heat is trapped, absorbed and stored by materials with high thermal mass (usually bricks or concrete)
inside the house. It is released at night when needed to warm up the building as it loses heat to the cooler outdoors.
Shading provided by trees or shades keeps the sun out in the hot months.
sty, Summer
Good roof and S - exclusion
ceiling insulation e .- oe
“7i* ' )
Avoid hot yY.7 ils,
summer and ye ©:
cold winter ‘ An
—_— f Winter
‘* maximum
* penetration
iduous trees
are good for sun
control
Well insulated heavyweight
internal walls
Passive Solar Design Source:
Lighting
Well-designed lighting can minimize the use of energy. This includes enhancing day lighting (natural light),
through windows, skylights, etc. Using energy efficient lighting such as compact fluorescent light bulbs and LEDs
(light-emitting diodes) can save energy as well. Using occupancy sensors also means that lights will only be on
when someone is in a room. See Module Sustainable Energy Practices: Climate Action Planning for more energy-
saving technologies that can be incorporated into buildings.
Water
Water usage can be minimized by using low-flow fixtures in restrooms, bathrooms, and kitchens. Dual-flush toilets
allow for the user to have the option of select less water (e.g. for liquid waste) and more water (e.g. for solid
waste) when flushing (See Figure Dual Flush Toilet). These have long been in use in Europe, the Middle East and
other places where water conservation is paramount. Fresh water consumption can be reduced further through the
use of greywater systems. These systems recycle water generated from activities such as hand washing, laundry,
bathing, and dishwashing for irrigation of grounds and even for flushing toilets.
Dual-flush Toilet This toilet has two flush
controls on the water tank. Pushing only the
circular button releases half as much (0.8 gallons,
3 liters) water as pushing the outer button. Source:
By Eugenio Hansen, OFS (Own work) [CC-BY-
SA-3.0],via Wikimedia Commons
Integrated Design
Integrated design is a design process for a building that looks at the whole building, rather than its individual parts,
for opportunities to reduce environmental impact. Incremental measures would include those approaches described
above. To accomplish integrated design of a building, all parties involved in the design--architects, engineers, the
client and other stakeholders--must work together. This collaborative approach results in a more harmonious
coordination of the different components of a building such as the site, structure, systems, and ultimate use.
Standards of Certification
Most countries establish certain standards to assure consistency, quality and safety in the design and construction
of buildings. Green building standards provide guidelines to architects, engineers, building operators and owners
that enhance building sustainability. Various green building standards have originated in different countries around
the world, with differing goals, review processes and rating. In this section we will discuss a few examples.
A good certification system should be developed with expert feedback. In addition, it should be transparent,
measurable, relevant and comparable.
e Expert-based: Was input acquired from experts and professionals in the fields of design, construction,
building operation and sustainability?
Transparent: Is information readily available to the public about how buildings are rated?
Measurable: Does the rating system use measurable characteristics to demonstrate the extent of sustainable
design incorporated into the building? Does the system use life-cycle analysis to evaluate?
e Relevance: Does the rating system provide a “whole building evaluation” rather than an evaluation of an
individual design feature?
Comparable: Is the rating system able to compare building types, location, years, or different sustainable
design features?
Year Country Trans- Expert- Measurable/
System established of origin parent based Uses LCA Relevance Con
BREEAM 1990 UK v* - v v v
ae 1996 Canada V v viv v v
Globes
LEED 2000 US v v vv V 3.0 v v
CASBEE 2001 Japan v v viv v v
ENERGY " Only
STAR 1999 US v Vv v aires v
*Only assessment prediction check lists available publicly
*Benchmarking tool developed by US EPA
Comparison of Certification Systems Source: Klein-Banai, C.
Conclusion
The built environment is the largest manifestation of human life on the planet. Buildings have been essential for
the survival of the human race, protecting us from the elements and forces of nature. However, they also consume
a lot of material, energy and water, and they occupy land that might otherwise be undeveloped or used for
agriculture. There are many ways to reduce that impact by building to a higher standard of conservation and reuse.
There are a number of systems that can help architects, engineers, and planners to achieve those standards, and
they should be selected with a full awareness of their limitations.
References
Fowler, K.M. & Rauch, E.M. (2008). Assessing green building performance. A post occupancy evaluation of 12
GSA buildings. (U.S. General Services Administration). PNNL-17393 Pacific Northwest National Laboratory
Richland, Washington. Retrieved from http://www.gsa.gov/graphics/pbs/GSA_ Assessing Green Full Report.pdf
Horvath, A. (2004). Construction materials and the environment. Annual Review of Energy and the Environment,
29 , 181-204.
Humphreys, K. & Mahasenan, M. (2002). Toward a Sustainable Cement Industry. Substudy 8, Climate Change.
World Business Council for Sustainable Development. Retrieved from
Kats, G., Alevantis, L., Berman, A., Mills, E. & Perlman, J. (2003). The costs and financial benefits of green
building: A report to California’s sustainable building task force. Retrieved from
http://www.usgbc.org/Docs/News/News477.pdf
Turner, C. & Frankel, M. (2008). Energy performance of LEED for New Construction Buildings, Final Report.
4-08b.pdf
U.S. Department of Energy. (2011). Energy savers: Furnaces and boilers. Retrieved from
http://www.energysavers.gov/your_home/space_heating cooling/index.cfm/mytopic=12530
U.S. Environmental Protection Agency. (1987). The total exposure assessment methodology (TEAM) study (EPA
600/S6-87/002). Retrieved from http://exposurescience.org/pub/reports/TEAM Study book 1987.pdf
U.S. Environmental Protection Agency. (1998). Characterization of building-related construction and demolition
debris in the United States. (Report No. EPA530-R-98-010). Retrieved from
http://www.epa.gov/wastes/hazard/generation/sqg/cd-rpt.pdf
U.S. Environmental Protection Agency. (2010). Green Building Basic Information. Retrieved from
http://www.epa.gov/greenbuilding/pubs/about.htm.
Review Questions
Exercise:
Problem: What are the positive and negative impacts that buildings have on the environment and society?
Exercise:
Problem: How can those impacts be reduced?
Exercise:
Problem:
What would be the advantages and disadvantages of demolishing an old building and replacing it with a new,
highly “sustainable” building vs. renovating an old building to new standards?
Glossary
deconstruction
The selective dismantling or removal of materials from buildings prior to or instead of conventional
demolition.
envelope
The physical barrier between the interior and exterior of a building including the walls, roof, foundation, and
windows.
greywater
The water generated from activities such as handwashing, laundry, bathing, and dishwashing that can be
recycled on-site to be used for irrigation of grounds and even for flushing toilets.
low-emissions
Materials that have little to no volatile organic compounds and other toxic chemicals that are released into the
environment after installation.
thermal mass
The ability of a material to absorb heat energy. High density materials like concrete, bricks and tiles need a lot
of heat to change their temperature and thus have a high thermal mass. Lightweight materials such as wood
have a low thermal mass.
Sustainable Energy Practices: Climate Action Planning
In this module, the following topics are covered: 1) the considerations
needed to make a move to a sustainable energy economy, 2) the path to get
to a sustainable energy economy, 3) sustainable energy policies and climate
action planning.
Learning Objectives
After reading this module, students should be able to
e understand the considerations needed to make a move to a sustainable
energy economy
e describe a path to get to a sustainable energy economy
¢ connect sustainable energy policies to climate action planning
Introduction
Traditionally, the United States has relied on fossil fuels with minimal use
of alternatives to provide power. The resources appeared to be unlimited
and they were found within our borders. As our population has grown and
our reliance on power increased, our resources are decreasing. As discussed
in Module Environmental Challenges in Energy, Carbon Dioxide, Air and
Water, this is particularly true of petroleum oil, which primarily powers
transportation. Our electrical grid and transportation infrastructure of roads
and highways support these fossil fuel dependent technologies. Fossil fuels
store energy well, are available upon demand (not weather dependent), and
are inexpensive. However, as we saw in Module Environmental Challenges
in Energy, Carbon Dioxide, Air and Water there are many environmental,
social, and even economic impacts of using these nonrenewable fuel
sources that are not accounted for in the traditional methods of cost
accounting. Further, the oil industry has been provided with many subsidies
or tax incentives not available to other energy industries.
How do we move to a more sustainable energy economy? We need to pay
more attention to the environment, humans, biodiversity, and respecting our
ecosystems. It means finding ways to share our resources equitably both
now and in the future so all people can have an equal opportunity to derive
benefits from electricity, motorized transportation systems, industry, and
conditioned indoor environments. At the same time, we must preserve
human health and protect the natural world.
Energy use is one big piece of the sustainability puzzle, but it is not the only
one. Changing the way we use energy is not easy because of infrastructure,
the vision of the American Dream (own a house with a big yard, a big car,
independence), changing government policy, lack of economic incentives,
etc. Goals need to be set, plans made, and policy set to change the way we
use energy. This chapter will discuss some of the commonly held views of
where we can start and how we can change.
Climate Action Planning as a Model
Since one of the major sustainability issues is that of climate change and the
major cause of climate change is energy use, climate action planning is a
valuable framework for examining sustainable energy practices.
Greenhouse gas emissions result primarily from our building and
transportation energy uses, and they are a measure of the amount of fossil
fuels used to provide that energy. They do not directly represent other
environmental emissions, although they mostly parallel other air pollutants.
Greenhouse gas emissions do not express other ecosystem effects such as
land use and water, but this planning allows for economical solutions. A
climate action plan provides a roadmap for achieving greenhouse gas
reduction targets within a specific timeline and uses a number of strategies.
Who is Doing Climate Action Planning?
In absence of federal regulation, cities, states, government institutions, and
colleges and universities, have all taken climate action initiatives. In
Massachusetts entities that generate more than 5,000 metric tons per year of
Carbon Dioxide Equivalent (CO e) began in 2010 with 2009 emissions.
emit more than 25,000 metric tons COze per year to start reporting in 2011
for 2010. Many cities have developed Climate Action Plans that set
greenhouse gas reduction goals and lay out pathways to achieve them.
Chicago launched its plan in 2008 and reports annually on its progress.
President Obama signed White House Executive Order 13514, in October
2009 requiring all federal agencies to appoint a sustainability director, take
inventory of greenhouse gas emissions, and work to meet sustainability
targets. Over 670 American colleges and universities have signed the
American College and University Presidents’ Climate Commitment
(ACUPCC) that requires them to develop climate action plans. Private
industries also develop climate action plans.
The National Wildlife Federation suggests that there are six steps to reduce
carbon emissions at universities — this could be similar for any other entity:
1. Commitment to emissions reduction
2. Institutional structures and support
3. Emissions inventory
4. Developing the plan
5. Launching the plan
6. Climate action planning over the long haul
Based on the climate change scenarios calculated by the Intergovernmental
Panel on Climate Change, it is recommended to reduce greenhouse gas
emissions to 80 percent below the 1990 levels, whether or not there is
continued growth. This is an absolute reduction to prevent greenhouse gases
from reaching levels that will have severe effects. A climate action plan is
made of a number of strategies to achieve that goal. To examine the impact
of each strategy the wedge approach is used. Developed by two professors
at Princeton, Socolow and Pacala, the approach proposes that in order to
reach those levels, emissions must be decreased globally by seven gigatons
of carbon (not carbon dioxide) compared to "business as usual" (BAU)
scenarios which would increase emissions over time due to growth and
professors identified 15 proposed actions that could each reduce emissions
by 1 gigaton, and if we could enact seven of them we would achieve the
represented by a "wedge" of the triangle, hence the designation of the
"wedge approach."
The Wedge Approach The upper figure (a) represents the current path
of increasing carbon emissions and the lower figure (b) represents the
effects of many different strategies used to reduce the emissions (a
wedge of the triangle). Source: The Carbon Mitigation Initiative,
Princeton University
iumedge
wous
8 1 Dilton tons of
camer emesions
i peryearoy 2060
2000 2050
Figure 2
Sustainable Solutions
All of the proposed solutions in Sokolov and Pacala’s proposal are existing
technologies. However, for a solution to be sustainable it must be
economically viable. Another aspect of developing a plan is the cost of the
solutions. Figure Global GHG Abatement Cost Curve Beyond Business-
As-Usual — 2030 shows the amount of greenhouse gas emissions that can be
abated beyond "business as usual" in 2030, along with the costs of different
abatement strategies. Those technologies that fall below the 0 line will
actually have a negative cost or positive economic benefit. Those
technologies that rise above the 0 line will have positive cost associated
with them which could be offset by the technologies that fall below the line.
Global GHG abatement cost curve beyond business-as-usual - 2030
Abatement cost Prd oes aaa
baad — Iron and steel CCS new build
60 Low penetration wind
Cars plug-in hybrid
Degraded forest reforestation
Coal CCS new build
Power plant biomass
co-firing
50 | Residential electronics
Residential appliances Nuclear Pn glen
Retrofit residential HVAC Pastureland afforestation High penetration wind
Tillage and residue mgmt Degraded land restoration Solar PV
Insulation retrofit (residential) 2” 9°". biofuels Solar CSP
Building effici
uilding ciency
Cars full hybrid new bui
Waste recycling
10 15 20 25 30 35 38
Organic soil restoration
Geothermal Abatement potential
Grassland management GtCO, e per year
Reduced pastureland conversion
Reduced slash and burn agriculture conversion
Small hydro
1St generation biofuels
Rice management
Efficiency improvements other industry
~ Electricity from landfill gas
Clinker substitution by fly ash
Cropland nutrient management
Motor systems efficiency
-90 Insulation retrofit (commercial)
Lighting - switch incandescent to LED (residential)
Note: The curve presents an estimate of the maximumpotential of all technical GHG abatement measures below €60 per tCO, emissions of each never was pursued
aggressively. It is not a forecast of what role different abatement measures and technologies will play.
Global GHG Abatement Cost Curve Beyond Business-As-Usual —
Economy. Version 2 of the Global Greenhouse Gas Abatement Cost
Curve, 2009
The types of technologies that fall below the line are primarily energy
conservation and efficiency technologies. Energy conservation is the act of
reducing energy use to avoid waste, save money, and reduce the
environmental impact. In the framework of sustainable energy planning it
allows the more expensive alternatives, such as renewables, to become
more advanced and cost-effective, while we conserve as much as possible.
Conservation has a behavioral aspect to it, such as turning off lights when
not needed, lowering thermostats in the winter, or keeping the proper air
pressure in a vehicle’s tires. There is a very low cost to conservation but it
entails behavioral change. There are technologies such as motion detectors
that can control lights or programmable thermostats that adjust temperature
that can help overcome the behavioral barrier. Energy efficiency can be
seen as a subset of conservation as it is really about using technological
advancements to make more efficient energy-consuming equipment.
In the United States we use twice as much energy per dollar of GDP as
most other industrialized nations (see Figure Energy Demand and GDP Per
Capita (1980-2004)). There are many reasons for this. One reason is that we
use less efficient vehicles and use proportionally more energy to heat and
cool buildings, behaviors that could be modified to be more efficient.
SSS
Primary Energy per capita (GJ)
0 5,000 10,000 15,000 20,000 25,000 30,000 35,000 40,000
GDP per capita (PPP, $2000)
Source: UN and DOE EIA, Russia data 1992-2004 only
Energy Demand and GDP Per Capita (1980-2004) Each line
represents a different country and the points are for the years 1980-
2004, which the exception of Russian which is 1992-2004. Source:
U.S. Department of Energy, Sustainability and Maintaining US
Competitiveness (June 2010), p. 4
U.S. Energy Consumption by Source Figure shows United
States energy consumption by source, with breakdown for
Another reason that the United States uses so much more energy than other
industrialized countries has to do with heating, cooling, and illuminating
buildings. Buildings account for about 40 percent of total energy
consumption in the United States (costing $350 billion per year) and
greenhouse gas emissions (see Figure U.S. Energy Consumption by
Source). Energy use in buildings is primarily for heating, cooling, and
illumination, with significant differences between commercial and
residential buildings. The rest of the energy use is for equipment such as
office equipment, electronics, refrigeration, cooking, and washing. There
are Many ways to save energy in existing buildings and most of them have a
good financial benefit of saving money on the energy costs, i.e. they have a
short term financial payback, or return on investment (ROI).
Start with the Lights
The most prevalent message in energy efficiency is "change the light
bulbs." Replacing traditional incandescent light bulbs with compact
fluorescent light bulbs can save energy. The light bulb had not evolved
much since Thomas Edison perfected it in 1879. Over the last few years
there have been major initiatives across the United States to replace
inefficient incandescent light bulbs with compact fluorescent light bulbs
(CFLs) that can reduce energy use by 75 percent. The light bulbs also last
10 times as long, reducing waste and maintenance costs. In commercial
buildings more efficient fluorescent light bulbs (T-8s) and ballasts are
replacing the older T-12s. In 2002, the U.S. Department of Energy required
that T-12 ballasts no longer be manufactured, ending a five year phase out
of this technology.
Compact
Fluorescent Light
Bulb Over its
lifetime, each
standard (13 watt)
CFL will reduce
electricity bills by
about $30 and
emissions from 200
lbs of coal over its
lifetime. Source:
Kevin Rector
Already newer, more efficient technologies are hitting the market — light-
emitting diodes (LEDs) — which use less than 25 percent of the energy of an
incandescent light and last at least 15 times longer, if it has the ENERGY
STAR rating. ENERGY STAR is the government-backed symbol for energy
efficiency recognition. LEDs are small light sources that become
illuminated by the movement of electrons through a semiconductor material
(Figure Solid State Lighting (SSL)). The technology is still evolving and
not all LED lights are created equally. LEDs are more expensive and will
have a longer pay back time, but they also last longer.
ei
Solid State Lighting (SSL) Solid state lighting (SSL)
is comprised of many small LEDs. Since they release
very little energy as heat, they are cool to the touch
and highly efficient. Source: Ocrho
If CFLs were used in all homes, the most advanced linear fluorescent lights
in office buildings, commercial outlets and factories, and LEDs in traffic
lights would reduce the percentage of electricity used for lighting in the
world from 19 percent to sever percent. That’s equivalent to 705 coal-fired
power plants.
Buy More Efficient Equipment and Appliances
ENERGY STAR also ranks equipment for efficiency from refrigerators to
air conditioners to computers and televisions. Policies and financial
incentives encourage people to buy more energy efficient products which
tend to be more expensive. However, by saving on energy costs consumers
can recuperate the investment. Refrigeration makes up 9 percent of
household energy use. Refrigerators have gotten more efficient from 3.84
cubic feet per kilowatt hour per day in 1972 to 11.22 cubic feet per kilowatt
hour by 1996 (Figure Average Efficiency of New Refrigerators in the
United States (1972-1997)). The efficiency of an average new refrigerator
has increased dramatically. New technology, increasing price of electricity,
and anticipated energy efficiency standards contributed to increased
efficiency in new refrigerators. The National Appliance Energy
Conservation Act of 1987 set minimum efficiency standards for 13 product
types, including refrigerators. After 1993, no refrigerator could be sold that
did not meet the standards. Standards were updated again in 2002.
However, 3 percent more households had two or more refrigerators in 2001
compared to 1980, partially reducing the effect of increased efficiency,
especially since the second refrigerator tends to be less efficient.
Today, consideration should be given to electronics in purchasing. Laptops,
for instance use considerably less electricity than desktops and flat screens
less than the old cathode ray tube (CRT) monitors. New HD televisions use
more energy than older analog TVs. Also, there are many appliances that
even if turned off, draw power from the grid. This is sometimes called
phantom load or vampire power. Although it is a small amount, it can
comprise up to 10 percent of home electricity use. Chargers for cell phones,
digital cameras, computers, and power tools are very common sources of
phantom load. Also, TVs, computer monitors, and DVD players have
current whenever they are plugged in. Using a "smart" power strip can
eliminate the need to manually up-plug. Plugging everything in to a strip
that is control by one master device or activated by a motion detector
provides the technology to replace the behavior of manually turning off and
unplugging all the devices when they are not in use.
fppliance Efficiency Standards in
force 19593
&
g
E
z
3
&
5
Average Efficiency of New Refrigerators in the
United States (1972-1997) Graph shows the efficiency
of an average new refrigerator in the United States from
1972 to 1997. Source: U.S. Energy Information
Administration
Tighten Up the Building Envelope
The building envelope (e.g. walls, windows, foundations, doors, and roofs)
greatly affects how efficient a building will be in maintaining comfortable
interior temperatures. Insulation in walls and seals around windows and
doors are prime factors. Low-emittance coatings (microscopically thin,
virtually invisible, metal or metallic oxide layers deposited on a window or
skylight glazing surface primarily to reduce the U-factor by suppressing
radioactive heat flow), gas-fills, and insulating spacers and frames can
significantly reduce winter heat loss and summer heat gain through
windows.
Double-pane, insulated glass windows significantly reduce the load on the
heating and cooling systems and drafts, which in turn, reduces energy
demand. These projects are most financially beneficial when leveraged as
part of other renovation projects. Existing windows can also be "fixed" with
weather-stripping and caulking to seal them from air leakages. Good storm
windows over single-pane glass windows can also provide similar
insulation to double-pane without the need for the larger financial
investment and the creation of waste that replacement entails.
Insulation in the attic or roof of a building and at the "seam" of the building
between the basement and first floor, as well as the walls can be installed or
increased to retain the heated or cooled air for building or home. Related to
insulation is sealing of opening to prevent air from leaking out (see Figure
Diagram of a Leaky Home).
ACECESSED
Lichts |
CRAWL SPACE
Le
Air leaking into the house
from outdoors.
Air leaking from inside
the house to the outside.
Diagram of a Leaky Home Diagram shows the various points in a
home where energy may leak. Source: EN!
Maintain or Upgrade Heating, Ventilation and Air-Conditioning
Systems
Heating, ventilation, and air-conditioning systems in commercial and
industrial buildings need to be properly monitored and maintained for the
most efficient function. This is often not done well after a system is
installed because not enough resources are dedicated to maintenance of
systems. Processes related to building commissioning make sure that
buildings are ready for service after equipment installation and testing,
problems are identified and corrected, and the maintenance staff is
extensively trained. If this was not done or the effect has worn out,
buildings may undergo recommissioning, or if it was never commissioned,
retrocommissioning can be performed.
If equipment such as motors, fans, boilers, and chillers are too old to fix or
inefficient, they can be replaced or retrofitted with more energy efficient
equipment. Building automation systems (BAS) use electronic technology
to control and monitor building systems. They can schedule temperature
settings and ventilation needs based on actual or scheduled occupancy so
energy can be saved when space is unoccupied. In homes, this is typically
done with a programmable thermostat that can set the temperature points to
conserve energy during the day when a home is unoccupied and then go
back to occupancy settings when the family returns.
Energy consulting companies can provide many services and innovative
solutions for building owners that will reduce energy costs. This is a
growing job sector within the United States economy as businesses try to
capitalize on the savings that energy projects like those described above can
provide.
Combining Heat and Power
One area of huge potential for energy efficiency is from capturing waste
heat from electricity generation and many industries through a process
called cogeneration or combined heat and power (CHP), which is discussed
in greater detail in the Module Combined Heat and Power. Cogeneration is
the simultaneous production of heat and electrical power in a single
thermodynamic process. Instead of discarding the heat produced by the
electrical power production or industrial process, it is captured and used to
provide space heating and hot water heating, humidification, cooling (via
absorption chillers), as well as other uses, thus eliminating the added
expense of burning fuels for the sole purpose of space heating (see Figure
Comparison of Energy Efficiency of Standard Power Plant and Combined
Heat and Power Plant). The U.S. Department of Energy calculated that CHP
generation from industrial processes alone is equal to the output of 40
percent of coal-fired generating plants that produced electricity in 2007.
40%
“Waste” heat released to environment
Standard
Power Plant
60%
Useful energy produced
100% > ‘add for electricity
fuel input
20%
“Waste” heat released to environment
Combined 40%
Heat and => Useful energy produced
Power Plant for heating and cooling via
power plant
=
100% = Useful energy produced
fuel input
for electricity
Comparison of Energy Efficiency of Standard Power
Plant and Combined Heat and Power Plant Diagram
compares the energy efficiency of a standard power plant
with a combined heat and power plant. Source: Cindy
Klein-Banai
Design New Buildings to Reduce Energy Use
The construction of new buildings consumes a lot of energy from the
production of the raw materials, the transportation to the building site, the
construction process, and ultimately the energy used to operate the building.
In the last decade in the United States, there has been a growing recognition
that much could be done to reduce the environmental impact of new
construction. Therefore, building energy codes increasingly demand higher
energy efficiency and green building certification and recognition systems
have been developed, such as Green Globes and Leadership in Energy and
Environmental Design (LEED), to promote design for the environment.
Aspects of construction that can enhance energy efficiency include site
selection, energy and water efficiency, materials used, proximity to public
transit and provision of biking amenities, and renewable energy. In addition,
using a process of integrated design where the structure of the building
itself provides the energy needed to heat, cool or illuminate the building,
energy savings can be achieved more readily.
Lincoln Hall, LEED Gold Certified,
University of Illinois at Chicago Lincoln Hall,
LEED Gold certified building on the University
of Illinois at Chicago campus. Features include
geothermal heating and cooling, solar
photovoltaic rooftop system, low-emittance,
high-U windows, daylighting, native planting,
bioswales for stormwater management, and use
of recycled materials. Source: UIC Office of
Implementing Renewable Energy Technologies
When buildings have been retrofitted to be more energy efficient and
combined heat and power systems are used more broadly, we will have
reduced energy demand significantly and cost effectively, while creating
more jobs domestically. We can then look at the mass deployment of
renewable energy technologies. Over time these technologies will mature
and become more affordable. This process can be enhanced through policy
implementation that incentivizes renewable energy development.
The electric grid will need to be expanded. This will allow for more
interstate transmission of renewable electricity from the areas where the
resources are good such as the southwest, for solar, and the central and
plains states, for wind, to the areas where the population centers are such as
the east and west coasts. If these grids are smart and allow for real-time
energy pricing then demand will be leveled out. This unified national smart
grid would include more efficient, higher-voltage long-distance
transmission lines; "smart" distribution networks that use the internet to
connect smart meters in homes and along the grid; energy storage units (i.e.
batteries) throughout the network; and two-way communication between
the equipment that consumes electricity and the equipment that produces it.
We can envision a future where most cars on the road are electric. At night,
consumption across the grid is lower because lights are off, buildings are
closed, and less manufacturing occurs. Owners of electric cars will plug
their cars into the grid at night and recharge them after being driven during
the day. Since, demand for electricity is lower, prices for this utility will be
lower. With smart meters, residents will be charged for the actual cost of
electricity at time of use rather than an average price. They will be
incentivized to set washing machines and dishwashers to run at night when
electricity demand is lowest. All of this evens out the demand on the grid,
which means that power plants do not need to operate at peak capacity and
reduces the need for new plants.
Energy Savings in Transportation
Transportation comprises nearly a third of energy demand in the United
States so energy savings achieved here will translate to overall energy
savings.To reduce energy consumption by vehicles we need to encourage
vehicle efficiency and conservation. This is accomplished through the
enacted these standards in 1975 due to the rising cost of gas that resulted
from the country’s dependence on increasing levels of petroleum imports.
The National Highway Traffic Safety Administration sets fuel economy
standards for cars and light trucks sold in the United States while the EPA
calculates the average fuel economy for each manufacturer. In addition to
CAFE standards, in 1975 the speed limit on United States highways was
reduced to 55 mph to limit gas consumption. Figure Carbon Dioxide
Emissions and Fuel Economy by Model Year shows that model year 2009
had the lowest CO» emission rate (397 g/mi) and highest fuel economy
(22.4 mpg) since tracking began in 1975.
Adjusted CO, Emissions by Model Year Adjusted Fuel Economy by Model Year
700 e 24 Cars
3 5 22
© _ 600 3 — Both
BE Trucks oe
BS 500 ce ®
35 —
3 Both 3 16 Trucks
on
3 14
400 Zz
Cars z 12
1975 1980 1985 1990 1995 2000 2005 2010 1975 1980 1985 1990 1995 2000 2005 2010
Model Year Model Year
Carbon Dioxide Emissions and Fuel Economy by Model Year Two
graphs show carbon dioxide emissions and fuel economy by model
year from 1975-2010. Source: U.S. EPA, Light-Duty Automotive
Technology, Carbon Dioxide Emissions, and Fuel Economy Trends:
1975 through 2010 (Nov. 2010), _p. iv
Other ways to increase efficiency can be found through innovative
alternative vehicle technologies, improved internal combustion engines,
exhaust gas recycling, variable valve timing, vehicle downsizing,
lightweighting, and behavior. Government policies need to make the cost
of driving evident through full amortization, fuel/road tax, and insurance
costs.
Another tactic to reduce fuel consumption is increasing the use of
transportation alternatives. The use of active transportation will cause a
change from environmentally harmful, passive travel to clean, active travel
by bicycle, foot, and public transit. Convenient and safe public transit is not
available in all communities, as it requires a certain population density to be
viable. Moreover, since Americans often associate the car they drive with
their material success and our communities are spread out, many people do
not view public transportation favorably. Most metropolitan areas have
some kind of transit system to provide transportation to those who cannot
afford cars or cannot drive and/or to relieve traffic congestion. Historically,
the United States has not invested equally in road and public transportation
infrastructure meaning that often it is slower and more complicated to travel
by transit. However, transit use is generally more economical than owning
and driving a car. The American Public Transportation Association has
calculated the savings based on a two person-two car household going to
one-car. They found that riding public transportation saves individuals, on
average $9,656 annually, and up to $805 per month based on the January 5,
2011 average national gas price ($3.08 per gallon-reported by AAA) and
the national unreserved monthly parking rate. Savings for specific cities are
shown here.
Bicycling and walking are two forms of alternate transit that have no
environmental impact on energy demand. Many local governments are
devoting resources to adding bike routes and parking facilities to encourage
bicycling as a mode of transportation. Sidewalks and safe cross-walks are
prerequisites for safe walking.
There are some options for those who must drive to reduce their energy use.
Carpooling and car sharing are also options that lower the number of cars
on the road, while providing opportunities to travel by car when needed.
Improved social network-based car-pooling programs can help to match
riders with drivers in a dynamic way. Car sharing is a decentralized, hourly
car rental system that allows people who do not own cars, but occasionally
need one, to access a vehicle in proximity to their workplace or home.
Summary
There is no one silver bullet when it comes to solving the "energy problem"
or planning for climate action. There are many viable solutions and the
problem is so large that multiple pathways must be forged. The primary
challenge is to use energy more efficiently so little goes to waste. From
small actions like changing a light bulb, to large projects like CHP, the
potential is great and the financial payback rewarding. Increased vehicle
efficiency and active transportation are also strategies for reducing energy
use. Both within the building sector and the transportation sector we have
the greatest challenges to and potential for changing how we use energy
today. We have already started to make that transition from more stringent
CAFE standards to more green buildings. The challenge is to upscale all the
strategies to make a significant impact.
Review Questions
Exercise:
Problem:
What does the chart in Figure Energy Demand and GDP Per Capita
(1980-2004) tell us about developing countries such as China, India
and Brazil’s energy use? a) In comparison to developed countries. b)
Over time.
Exercise:
Problem:
Briefly describe a path to reducing our dependency on fossil fuels for
transportation energy consumption.
Exercise:
Problem:
Why is energy efficiency considered a sustainable energy choice?
References
Brown, L.R. (2008). Plan B 3.0: Mobilizing to save civilization. New York:
Earth Policy Institute.
City of Chicago. (2011). Chicago Climate Action Plan. Retrieved
September 12, 2011 from
http://www.chicagoclimateaction.org/filebin/pdf/finalreport/CCAPREPORT
FINALv2.pdt
Eagan, D.J., Calhoun, T., Schott, J. & Dayananda, P. (2008). Guide to
climate action planning: Pathways to a low-carbon campus. National
Wildlife Federation: Campus Ecology. Retrieved September 12, 2011 from
http://www.nwf.org/Global-Warming/Campus-
Solutions/Resources/Reports/Guide-to-Climate-Action-Planning aspx
Gore, A. (2009). Our choice: A plan to solve the climate crisis. New York:
Melcher Media.
Pacala, S. & Socolow, R. (2004). Stabilization wedges: Solving the climate
problem for the next 50 years with current technologies. Science, 305, 968-
O72:
University of Illinois at Chicago. (2009). UIC Climate Action Plan.
Retrieved September 12, 2011 from
http://www.uic.edu/sustainability/climateactionplan/.
Glossary
Active Transportation
Means of transportation that involve more physical activity, typically
considered walking, biking, and use of public transit (bus and rail).
Building Automation System (BAS)
Controls and monitors a buildings mechanical and lighting systems
through a computerized, intelligent network
devices.
Carpooling
When two or more people travel to and from proximal departure and
arrival destinations in the same vehicle.
Car Sharing
A program that allows for more than one person to have use of a Car.
Generally, it works like a short-term (hourly) car rental service. Cars
are located near residences and work places to facilitate the access to
the vehicles and to reduce the need for individual car ownership.
Lightweighting
Making a product out of materials that weigh less than were previously
used
Low-Emittance Coatings
Microscopically thin, virtually invisible, metal or metallic oxide layers
deposited on a window or skylight glazing surface primarily to reduce
the U-factor by suppressing radioactive heat flow.
Phantom Load or Vampire Power
Refers to the electrical load of appliances and chargers when they are
not in use but plugged in, as they still draw power but provide no
service.
U-factor
The rate of heat loss is indicated in terms of the of a window assembly.
The lower the U-factor, the greater a window's resistance to heat flow
and the better its insulating properties.
Wedge Approach
A way of expressing the concept that there is no one solution to the
challenge of reducing greenhouse gas emissions. Each technology,
action or change is represented by a triangular wedge in a chart of time
vs. emissions.
Sustainable Transportation: Accessibility, Mobility, and Derived Demand
In this module, the following topics are covered: 1) the unsustainability of
the automobile-based system of transportation 2) transportation as a derived
demand and 3) how accessibility and mobility are currently treated by our
transportation system.
Learning Objectives
After reading this module, students should be able to
e explain why the automobile-based system of transportation is
unsustainable in terms of inputs, outputs, and social impacts
e explain why transportation is a derived demand and how making
transportation sustainable depends on land use as well as vehicles and
infrastructure
e differentiate between accessibility and mobility by comparing how
they are currently treated by our transportation system
e analyze how a more sustainable system might address accessibility and
mobility
What is Sustainable Transportation?
Transportation is a tricky thing to analyze in the context of sustainability. It
consists in part of the built environment: the physical infrastructure of
roads, runways, airports, bridges, and rail lines that makes it possible for us
to get around. It also consists in part of individual choices: what mode we
use to get around (car, bus, bike, plane, etc.), what time of day we travel,
how many people we travel with, etc. Finally, it also is made up of
institutions: federal and state agencies, oil companies, automobile
manufacturers, and transit authorities, all of whom have their own goals and
their own ways of shaping the choices we make.
Most importantly, transportation is complicated because it's what is called a
derived demand. With the exception of joyriding or taking a walk or
bicycle ride for exercise, very rarely are we traveling just for the sake of
moving. We're almost always going from Point A to Point B. What those
points are—home, work, school, shopping—and where they're located—
downtown, in a shopping mall, near a freeway exit—influence how fast we
need to travel, how much we can spend, what mode we're likely to take, etc.
The demand for transportation is derived from other, non-transportation
activities. So in order to understand transportation sustainability, we have to
understand the spatial relationship between where we are, where we want to
go, and the infrastructure and vehicles that can help get us there.
Is our current transportation system in the U.S. sustainable? In other words,
can we keep doing what we're doing indefinitely? The answer is clearly no,
according to professional planners and academics alike. There are three
main limitations: energy input, emissions, and social impacts (Black, 2010).
Energy Inputs
The first reason that our current transportation system is unsustainable is
that the natural resources that power it are finite. The theory of peak oil
developed by geologist M. King Hubbert suggests that because the amount
of oil in the ground is limited, at some point in time there will be a
maximum amount of oil being produced (Deffeyes, 2002). After we reach
that peak, there will still be oil to drill, but the cost will gradually rise as it
becomes a more and more valuable commodity. The most reliable estimates
of the date of peak oil range from 2005 to 2015, meaning that we've
probably already passed the point of no return. New technologies do make
it possible to increase the amount of oil we can extract, and new reserves,
such as the oil shale of Pennsylvania and the Rocky Mountains, can supply
us for some years to come (leaving aside the potential for environmental
and social damage from fully developing these sites). However, this does
not mean we can indefinitely continue to drive gasoline-powered vehicles
as much as we currently do.
Scientists are working on the development of alternative fuels such as
biofuels or hydrogen, but these have their own limitations. For example, a
significant amount of land area is required to produce crops for biofuels; if
we converted every single acre of corn grown in the U.S. to ethanol, it
would provide 10% of our transportation energy needs. Furthermore,
growing crops for fuel rather than food has already sparked price increases
and protests in less-developed countries around the world (IMF,_2010). Is it
fair to ask someone living on less then two dollars a day to pay half again as
much for their food so we can drive wherever and whenever we want?
Emissions or Outputs
The engine of the typical automobile or truck emits all sorts of noxious
outputs. Some of them, including sulfur dioxides, carbon monoxide, and
particulate matter, are directly harmful to humans; they irritate our lungs
and make it hard for us to breathe. (Plants are damaged in much the same
way). These emissions come from either impure fuel or incomplete burning
of fuel within an engine. Other noxious outputs cause harm indirectly.
Nitrous oxides (the stuff that makes smog look brown) from exhaust, for
example, interact with oxygen in the presence of sunlight (which is why
smog is worse in Los Angeles and Houston), and ozone also damages our
lungs.
Carbon dioxide, another emission that causes harm indirectly, is the most
prevalent greenhouse gas (GHG), and transportation accounts for 23% of
the CO, generated in the U.S. This is more than residential, commercial, or
industrial users, behind only electrical power generation (DOE, 2009). Of
course, as was explained above, transportation is a derived demand, so to
say that transportation itself is generating carbon emissions is somewhat
misleading. The distance between activities, the modes we choose to get
between them, and the amount of stuff we consume and where it is
manufactured, all contribute to that derived demand and must be addressed
in order to reduce GHG emissions from transportation.
Social Impacts
If the definition of sustainability includes meeting the needs of the present
population as well as the future, our current transportation system is a
failure. Within most of the U.S., lack of access to a personal automobile
means greatly reduced travel or none at all. For people who are too young,
too old, or physically unable to drive, this means asking others for rides,
relying heavily on under-funded public transit systems, or simply not
traveling. Consider, for example, how children in the U.S. travel to and
from school. In 1970, about 50% of school-aged children walked or biked
At the same time that childhood obesity and diabetes are rising, children are
getting less and less exercise, even something as simple as walking to
school. Furthermore, parents dropping off their children at school can
increase traffic levels by 20 to 25%, not just at the school itself, but also
age spectrum, elderly people may be functionally trapped in their homes if
they are unable to drive and lack another means of getting to shopping,
health care, social activities, etc. Finally, Hurricane Katrina made it clear
that access to a car can actually be a matter of life or death: the evacuation
of New Orleans worked very well for people with cars, but hundreds died
because they didn't have the ability to drive away.
Another serious social impact of our transportation system is traffic
accidents. Road accidents and fatalities are accepted as a part of life, even
though 42,000 people die every year on the road in the U.S. This means that
cars are responsible for more deaths than either guns, drugs, or alcohol (Xu
et_al., 2010). On the bright side, there has been a steady reduction in road
fatalities over the last few decades, thanks to a combination of more safety
features in vehicles and stricter enforcement and penalties for drunk or
distracted drivers. Nevertheless, in many other countries around the world,
traffic accidents are in the top ten or even top five causes of death, leading
the World Health Organization to consider traffic accidents a public health
problem.
An additional problem with our current unsustainable transportation system
is that much of the rest of the world is trying to emulate it. The U.S. market
for cars is saturated, meaning that basically everyone who can afford or is
likely to own a car already has one. This is why automobile manufacturers
vie so fiercely with their advertising, because they know they are competing
with each other for pieces of a pie that's not getting any bigger. In other
countries such as China and India, though, there are literally billions of
people who do not own cars. Now that smaller, cheaper vehicles like the
Tata are entering these markets, rates of car ownership are rising
dramatically. While the same problems with resources, emissions, and
social impacts are starting to occur in the developing world, there are also
unique problems. These include a lack of infrastructure, which leads to
monumental traffic jams; a need for sharing the road with pedestrians and
animals; and insufficient regulation to keep lead and other harmful additives
out of gasoline and thus the air.
What Would Make Transportation Sustainable?
The circular answer to the question is to meet our current transportation
needs without preventing future generations from meeting theirs. We can
start by using fewer resources or using the ones we have more efficiently.
One way to do this is by increasing the efficiency of new vehicles as they
are manufactured. Since 1981, automotive engineers have figured out how
to increase horsepower in the average American light-duty vehicle (cars and
SUVs) by 60%, but they haven't managed to improve miles per gallon at all
(see Figure World Oil Production - History and Projections). As gas prices
continue to rise on the downside of the oil peak, consumers are already
demanding more fuel-efficient cars, and federal legislation is moving in this
direction to raise the Corporate Average Fuel Economy (CAFE) standards.
World Oil Production (History + Projections)
(Barrels/day) M@— Campbell: 0.953Th left, 2010 peak at 83mb/d
Peaks 2010-2035 - —Harper: 1.45tb left, 2015 peak at 89mb/d
World consumed ~960 Billion barrels: 1930-2004 M— USGS 50% - 2.06tb left, 2024 peak at 97mb/d
~0.95, 1.45, 2.06, 2.95 trillion barrels remaining Mi USGS 5%: 2.949tb left, 2033 peak at 108mb/d
Transition: 2% growth curve to 5% decay curve
4
Historical Production Future Production?
1930 1950 1970 1990 2010 2030 2050 2070 2090
World Oil Production - History and Projections Historical
production of oil (grey) and forecasts of future production (colors).
According to the "peak oil" hypothesis, world oil production will peak
and then decline. Estimates of future production vary widely as there is
disagreement about the magnitude of undiscovered reserves. If most of
the extractable oil has been discovered, we may have already reached
peak oil (orange curve). If significant undiscovered reserves remain,
peak oil may not arrive until 2030 or 2040. Source: Released to public
domain by Tom Ruen, via Wikimedia Commons
However, simply producing more fuel-efficient vehicles is not sufficient
when we consider the embodied energy of the car itself. It takes a lot of
energy to make a car, especially in the modern "global assembly line,"
where parts come from multiple countries for final assembly, and that
energy becomes "embodied" in the metal, plastic, and electronics of the car.
A study in Europe found that unless a car is over 20 years old, it does not
make sense to trade it in for a more efficient one because of this embodied
energy (Uson et al., 2011). Most Americans trade in their cars after about a
third of that time. A related concept is true for electric cars. In their daily
usage, they generate zero carbon emissions, but we should also consider the
source of power used to recharge the vehicle. In most parts of the U.S., this
is coal, and therefore the emissions savings are only about 30% over a
traditional vehicle (Marsh, 2011).
If transportation is a derived demand, another way to meet our current
transportation needs is by changing the demand. There are two related
aspects to this. First, there is a clear causal link between having more
transportation infrastructure and more miles traveled on that infrastructure,
and greater economic growth. This is true between regions of the world,
between individual countries, and between people and regions within
countries. This causal connection has been used as a reason to finance
transportation projects in hundreds of different contexts, perhaps most
recently in the American Reinvestment and Recovery Act that distributed
federal funds to states and localities to build infrastructure in the hopes that
it would create jobs. Policymakers, businesspeople, and citizens therefore
all assume that we need more transportation to increase economic growth.
However, it is also true that more transportation does not automatically
mean more economic growth: witness the state of West Virginia, with
decades' worth of high-quality road infrastructure bestowed upon it by its
former Senator Robert Byrd, but still at the bottom of economic rankings of
states. Furthermore, at some point a country or region gains no significant
improvements from additional infrastructure; they have to focus on making
better use of what they already have instead. We therefore need to decouple
economic growth from transportation growth (Banister and Berechman,
2001). We can substitute telecommunication for travel, work at home, or
shop online instead of traveling to a store (although the goods still have to
travel to our homes, this is more efficient than each of us getting in our own
cars). We can produce the goods we use locally instead of shipping them
halfway around the world, creating jobs at home as well as reducing
resource use and emissions. All of these options for decoupling are ways to
reduce the demand for transportation without also reducing the benefits
from the activities that create that demand.
The other way to think about changing the derived demand of transportation
is via the concepts of accessibility and mobility. Mobility is simply the
ability to move or to get around. We can think of certain places as having
high accessibility: at a major intersection or freeway exit, a train station,
etc. Company headquarters, shopping malls, smaller businesses alike decide
where to locate based on this principle, from the gas stations next to a
freeway exit to the coffee shop next to a commuter rail station. At points of
high accessibility, land tends to cost more because it's easier for people to
get there and therefore more businesses or offices want to be there. This
also means land uses are usually denser: buildings have more stories,
people park in multi-level garages instead of surface lots, etc.
We can also define accessibility as our own ability to get to the places we
want: where we shop, work, worship, visit friends or family, see a movie, or
take classes. In either case, accessibility is partially based on what the
landscape looks like—width of the roads, availability of parking, height of
buildings, etc.—and partially on the mode of transportation that people
have access to. If a person lives on a busy four-lane road without sidewalks
and owns a car, most places are accessible to him. Another person who lives
on that same road and doesn't have a car or can't drive might be literally
trapped at home. If her office is downtown and she lives near a commuter
rail line, she can access her workplace by train. If her office is at a major
freeway intersection with no or little transit service, she has to drive or be
driven.
ool ages EPA pe ces BE as 5 /
ied shoe ae | an
—
a +
/
Subdivision A modern subdivision near Markham, Ontario. The
suburb is residential only, and cars are the only visible means of
transport; accessibility for those without personal vehicles is low.
Photo by IDuke, November 2005. Source: [Duke (English Wikipedia)
[CC-BY-SA-2.5], via Wikimedia Commons
Unfortunately, in the U.S. we have conflated accessibility with mobility. To
get from work to the doctor's office to shopping to home, we might have to
make trips of several miles between each location. If those trips are by bus,
we might be waiting for several minutes at each stop or making many
transfers to get where we want to go, assuming all locations are accessible
by transit. If those trips are by car, we are using the vehicle for multiple
short trips, which contributes more to air pollution than a single trip of the
same length. Because of our land use regulations, which often segregate
residential, retail, office, and healthcare uses to completely different parts of
a city, we have no choice but to be highly mobile if we want to access these
destinations. John Urry has termed this automobility, the social and
economic system that has made living without a car almost impossible in
countries like the US and the UK (2004).
So how could we increase accessibility without increasing mobility? We
could make it possible for mixed uses to exist on the same street or in the
same building, rather than clustering all similar land uses in one place. For
example, before a new grocery store opened in the student neighborhood
adjacent to the University of Illinois campus in Champaign, people living
there had to either take the bus, drive, or get a friend to drive them to a
more distant grocery store. Residents of Campustown had their accessibility
to fresh produce and other products increase when the new grocery store
opened, although their mobility may have actually gone down. In a larger-
scale example, the Los Angeles Metropolitan Transit Authority (MTA) was
sued in the 1990s for discriminating against minorities by pouring far more
resources into commuter rail than into buses. Commuter rail was used
mainly by white suburbanites who already had high levels of accessibility,
while the bus system was the only means of mobility for many African-
American and Hispanic city residents, who had correspondingly less
accessibility to jobs, shopping, and personal trips. The courts ruled that the
transit authority was guilty of racial discrimination because they were
providing more accessibility for people who already had it at the expense of
those who lacked it. The MTA was ordered to provide more, cleaner buses,
increase service to major job centers, and improve safety and security. More
sustainable transportation means ensuring equitable accessibility — not
mobility — for everyone now and in the future.
Making Transportation Sustainable
How do we go about making transportation more sustainable? There are
three main approaches: inventing new technologies, charging people the full
costs of travel, and planning better so we increase accessibility but not
mobility.
New Technology
This is the hardest category to rely on for a solution, because we simply
can't predict what might be invented in the next five to fifty years that could
transform how we travel. The jet engine totally changed air travel, making
larger planes possible and increasing the distance those planes could reach
without refueling, leading to the replacement of train and ship travel over
long distances. However, the jet engine has not really changed since the
1960s. Is there some new technology that could provide more propulsion
with fewer inputs and emissions? It's possible. But at the same time, it
would be unreasonable to count on future inventions magically removing
our sustainability problems rather than working with what we already have.
Technology is more than just machines and computers, of course; it also
depends on how people use it. When the automobile was first invented, it
was seen as a vehicle for leisure trips into the country, not a way to get
around every day. As people reshaped the landscape to accommodate cars
with wider, paved roads and large parking lots, more people made use of the
car to go to work or shopping, and it became integrated into daily life. The
unintended consequences of technology are therefore another reason to be
wary about relying on new technology to sustain our current system.
Charge Full Costs
The economist Anthony Downs has written that traffic jams during rush
hour are a good thing, because they indicate that infrastructure is useful and
a lot of people are using it (Downs, 1992). He also notes that building more
lanes on a highway is not a solution to congestion, because people who
were staying away from the road during rush hour (by traveling at different
times, along different routes, or by a different mode) will now start to use
the wider road, and it will become just as congested as it was before it was
widened. His point is that the road itself is a resource, and when people are
using it for free, they will overuse it. If instead, variable tolls were charged
depending on how crowded the road was—in other words, how much
empty pavement is available—people would choose to either pay the toll
(which could then be invested in alternative routes or modes) or stay off the
road during congested times. The point is that every car on the road is
taking up space that they aren't paying for and therefore slowing down the
other people around them; charging a small amount for that space is one
way of recovering costs.
Freeway Traffic Typical congested traffic on an urban freeway — I-80
in Berkeley, California. Residents of U.S. cities typically require
automobiles to experience mobility. Note the externalities that the
drivers are imposing on others such as air pollution and congestion.
The left lane is for car-pooling — as marked by the white diamond — an
attempt to address the congestion externality. Source: By User
Minesweeper on en.wikipedia (Minesweeper) CC
>)
Traffic congestion is an example of what economists call externalities, the
costs of an activity that aren't paid by the person doing the activity.
Suburbanites who drive into the city every day don't breathe the polluted air
produced by their cars; urban residents suffer that externality. People
around the country who use gasoline derived from oil wells in the Gulf of
Mexico didn't experience oil washing up on their beaches after the BP
disaster in 2010. By charging the full cost of travel via taxes on gas or
insurance, we could, for example, pay for children's hospitalization for
asthma caused by the cars speeding past their neighborhoods. Or we could
purchase and preserve wetland areas that can absorb the floodwaters that
run off of paved streets and parking lots, keeping people's basements and
yards drier. Not only would this help to deal with some of the externalities
that currently exist, but the higher cost of gas would probably lead us to
focus on accessibility rather than mobility, reducing overall demand.
Planning Better for Accessibility
The other way we can produce more sustainable transportation is to plan for
accessibility, not mobility. Many transportation planners say that we've been
using the predict and provide model for too long. This means we assume
nothing will change in terms of the way we travel, so we simply predict
how much more traffic there is going to be in the future and provide roads
accordingly. Instead, we should take a deliberate and decide approach,
bringing in more people into the planning process and offering different
options besides more of the same. Some of the decisions we can make to try
and change travel patterns include installing bike lanes instead of more
parking, locating retail development next to housing so people can walk for
a cup of coffee or a few groceries, or investing in transit instead of
highways.
Traditional Plaza A traditional city center in Piran, Slovenia. The
region around the square is mixed use, with buidlings serving both
residential and commercial functions. The square is highly accessible
to residents. Source: Plamen Agov studiolemontree.com.
For example, the school district in Champaign, Illinois, is considering
closing the existing high school next to downtown, to which many students
walk or take public transit, and replacing it with a much larger facility on
the edge of town, to which everyone would have to drive or be driven. The
new site would require more mobility on the part of nearly everyone, while
many students and teachers would see their accessibility decrease. As gas
prices continue to rise, it will cost the school district and parents more and
more to transport students to and from school, and students will be more
likely to drive themselves if they have access to a car and a driver's license.
Putting the new school in a more accessible location or expanding the
existing one would keep the school transportation system from becoming
less sustainable.
You may have noticed that these proposed changes to increase
transportation sustainability aren't really things that one person can do. We
can certainly make individual choices to drive less and walk or bike more,
to buy a more fuel-efficient car, or to use telecommunications instead of
transportation. In order to make significant changes that can reduce overall
energy usage and emissions production, however, the system itself has to
change. This means getting involved in how transportation policy is made,
maybe by attending public meetings or writing to city or state officials
about a specific project. It means contacting your Congressional
representatives to demand that transportation budgets include more money
for sustainable transportation modes and infrastructure. It means advocating
for those who are disadvantaged under the current system. In means
remembering that transportation is connected to other activities, and that
focusing on how the demand for transportation is derived is the key to
making and keeping it sustainable.
Review Questions
Exercise:
Problem:
Explain the concept of a derived demand and how it accounts for the
connections between transportation and land use planning.
Exercise:
Problem:
What is the concept of embodied energy? Why does it suggest that
switching to electric cars is not a surefire way to make transportation
more sustainable?
Exercise:
Problem:
Give an example in your daily life that could be used to explain the
difference between accessibility and mobility.
References
Appleyard, B. S. 2005. Livable Streets for School Children: How Safe
Routes to School programs can improve street and community livability for
children. National Centre for Bicycling and Walking Forum, available
Banister, D. and Berechman, Y. 2001. Transport investment and the
promotion of economic growth. Journal of Transport Geography 9:3, 209-
218.
Black, W. 2010. Sustainable Transportation: Problems and Solutions. New
York: Guilford Press.
Deffeyes, K. 2002. Hubbert's Peak: The Impending World Oil Shortage.
Princeton, NJ: Princeton University Press.
DOE (Department of Energy). 2009. Emissions of greenhouse gases report.
DOE/EIA-0573, available online:
http://www.eia.doe.gov/oiaf/1605/g¢grpt/carbon. html
Downs, A. 1992. Stuck in Traffic: Coping With Peak-Hour Traffic
Congestion. Washington, DC: Brookings Institution Press.
IMF (International Monetary Fund). 2010. Impact of high food and fuel
prices on developing countries. Available online:
Maring, G. 2007. Surface transportation funding issues and options.
Presentation to the National Surface Transportation Infrastructure Financing
Commission. Available online:
http://financecommission.dot.gov/Documents/Surface%20Transportation%
20Funding%20Issues%20and%20Options Gary%20Maring ppt
Marsh, B. 2011. Kilowatts vs. Gallons. New York Times, May 28. Available
online: http://www.nytimes.com/interactive/2011/05/29/weekinreview/Vvolt-
graphic. html ?ref=weekinreview
UPI (United Press International). 2011. Global biofuel land area estimated.
Available online: http://www.upi.com/Science_News/2011/01/10/Global-
biofuel-land-area-estimated/UPI-97301294707088/
Urry, J,. 2004. The 'System' of Automobility. Theory Culture and Society
21:4-5, 25-39.
Uson, A.A., Capilla, A.V., Bribian, I.Z., Scarpellini, S. and Sastresa, E.L.
2011. Energy efficiency in transport and mobility for an eco-efficiency
viewpoint. Energy 36:4, 1916-23.
Xu, J., Kochanek, K., Murphy, S., and Tejada-Vera, B. 2010. Deaths: Final
Data for 2007. National Vital Statistics Reports, 58:19, available online:
http://www.cdc.gov/NCHS/data/nvsr/nvsr58/nvsr58_19.pdf
Glossary
accessibility
In transportation, a measure of the ease with which people are able to
get places they want or need to go.
derived demand
Demand for a good or service that comes not from a desire for the
good or service itself, but from other activities that it enables or desires
it fulfills.
embodied energy
The sum of all energy used to produce a good, including all of the
materials, processes, and transportation involved.
externality
Cost of an activity not paid by the person doing the activity.
mobility
The ability to move or to get around.
Sustainable Stormwater Management
In this module, the following topics will be covered: 1) the affects of
stormwater runoff on water quality in urban watersheds; 2) the management
of stormwater in the United States; and 3) some techniques that have been
developed to address the water pollution and flood risks associated with
urban stormwater runoff.
Learning Objectives
After reading this module, students should be able to
¢ describe how stormwater runoff affects water quality in urban
watersheds
e explain how stormwater is currently managed in the United States
e analyze some of the conventional and innovative techniques that have
been developed to address the water pollution and flood risks
associated with urban stormwater runoff
Introduction
This module reviews some of the complex issues of urban stormwater
management. It first examines the hydrological issues affecting the
discharge of stormwater runoff to our urban rivers and streams, and then
provides an overview of how urban stormwater is managed under the Clean
Water Act. After describing the conventional approaches to urban
stormwater management, the final section provides an overview of various
"sustainable" strategies, especially the use of "green infrastructure," that can
be considered to reduce the water pollution and flooding risks generated by
urban stormwater runoff.
The Hydrological Context of Urban Stormwater
Stormwater runoff (or overland flow) is the portion of precipitation
reaching the ground that does not infiltrate into soils, is not taken up and
transpirated by plants, nor is it evaporated into the atmosphere. It is an
especially important component of the hydrological cycle in urban areas,
since it can cause both pollution and flooding risks to nearby waterways
and their adjacent communities. It should also be noted that many of the
current models of global climate change predict changes in the hydrological
cycle in the future. They predict many more severe storms likely in parts of
the Midwest as a result of the moisture and energy in the atmosphere
increasing over the next century because of increasingly higher
concentrations of greenhouse gases. Higher frequencies of more severe
storms are likely to further increase the pollution and flooding risks posed
by stormwater runoff, especially in urban areas (USGCRP, 2009).
Current strategies to manage these risks employ the concept of a watershed
— the variations in natural topography that cause both surface water and
surficial ground water to flow downhill towards lower-lying areas or points
of discharge, usually to a stream or river. Watershed boundaries are defined
topographically by mapping variations in land elevations around waterways
that create hydrologic divides between adjacent watersheds and between
sub-watersheds. The amount of stormwater that ends up as runoff within a
watershed not only depends on the intensity and amount of precipitation
reaching the ground in the form of rain or snow, but also on the
characteristics of the watershed itself. State and federal environmental
protection agencies have developed a number of sophisticated hydrological
simulation models that enable the amount and characteristics of stormwater
runoff (in terms of its volume and the pollutant load that would be carried
by the stormwater to rivers and streams within the watershed) to be
forecasted. They forecast this based on historical estimates of the amount of
precipitation entering the watershed, the characteristics of a watershed's
terrain and soils, the amount and location of impermeable surfaces
associated with the development of the watershed, and the extent and types
of ground cover within the watershed's drainage area (NRC 2008, Appendix
D). A change in any of these factors will affect the amount and extent of
flooding and water pollution attributable to the discharge of stormwater
runoff into a river or stream.
Since the pattern of precipitation varies seasonally the water pollution and
flooding risks posed by stormwater runoff also tend to vary seasonally.
Generally, larger flood and pollution risks will occur in the spring, when
rapid snowmelt can generate a lot of runoff volume (especially if the ground
is still frozen), which can carry pollutants that have accumulated within the
snow cover over the winter months to nearby streams and rivers. There can
also be storm-related flood and pollution "spikes" when heavy rain strikes
the ground at a faster rate than it can be infiltrated into the soils, or when it
is prevented from infiltrating into the soils by roofs, paving, or other
impermeable surfaces. This initially high volume of stormwater runoff can
carry greater amounts of contaminants — a process often described as the
"first flush" phenomenon. Usually, the first half-inch of stormwater will
be carrying the highest pollution load, so its capture and management
becomes a priority for water quality protection.
How some of these features, especially the amount of impervious surface
associated with different densities of development, affect the generation of
urban runoff are illustrated in Figure Degrees of Imperviousness and its
Effects on Stormwater Runoff. Research by the Center for Watershed
Protection has found that stream quality becomes impaired when 10% of
the stream's watershed is impervious and that an urban stream's ecology is
severely impacted when more than 25% of its watershed is impervious.
40% evapotranspiration 38% evapotranspiration
” 20%
runoff
25% shallow 21% shallow
infiltration infiltration
” 10%
runoff
25% deep 21% deep
infiltration infiltration
Natural Ground Cover 10%-20% Impervious Surface
35% evapotranspiration 30% evapotranspiration
—s ee
BB Baan
ae Bean
aa -—: Bees
| an85
f 30% = 55%
runoff
aaa
20% shallow 10% shallow
infiltration infiltration
15% deep
5% deep
infiltration infiltration
35%-50% Impervious Surface 75%-100% Impervious Surface
Degrees of Imperviousness and its Effects on
Stormwater Runoff These four images show
increasing amount of stormwater runoff as the area
becomes developed with more impervious surfaces.
Source: In Stream Corridor Restoration: Principles,
When flowing downhill within a watershed, stormwater runoff can pick up
pollutants from various anthropogenic sources and activities. It can also
collect pollutants from the atmospheric deposition of particulates and air
pollutants carried to the earth's surface by precipitation, by windblown dust,
or by simply settling out of the atmosphere. Urban runoff can also dissolve
or transport chemicals that may be found naturally in soil or nutrients which
may have been deliberately added to lawns. Common urban pollutants can
include such things as pesticides and fertilizers applied to residential lawns,
parks and golf courses, enteric microbes from animal waste, industrial
chemicals that may have been accidentally spilled on the ground or
improperly stored, or oils and greases leaking from cars parked in lots or on
driveways.
As stormwater runoff flows towards lower-lying areas of the watershed, it
carries these contaminants with it and therefore contributes to the pollution
of the stream, river or lake into which it is discharging. Once it reaches a
river or stream, the concentrations of pollutants in the receiving waters are
naturally reduced as the contaminants are carried downstream from their
sources, largely through dilution but also by settlement, by uptake by
posure to sunlight and oxygen, and by interactions with various chemical
and physical proplants and animals (including bacteria and other
microorganisms), through degradation by excesses occurring within the
waterway and its streambed.
Regulating Urban Runoff
Water pollution risks within watersheds are managed under the federal
Clean Water Act, which requires state environmental protection agencies to
regulate the discharge of pollutants into navigable waterways and
waterbodies pursuant to federal guidelines (NRC, 2008). The Clean Water
Act employs maximum concentration standards for common pollutants that
can impair the recreational or ecological functions of a river or stream. One
class of polluters regulated under the Clean Water Act consists of those that
are directly discharging pollutants into a waterway from an industry or
sewage treatment plant through a pipe, ditch, outfall or culvert — these are
called point sources.
Point sourcesare managed under the Clean Water Act by the requirement
that each direct source have a renewable discharge permit, called a National
Pollution Discharge Elimination System (NPDES) permit. NPDES permits
set limits for the various pollutants being discharged by that source based
on the ambient water quality of the waterway and its proposed use (e.g. its
use as a public water supply source, or for fishing, or recreational use). The
other regulated class of polluters managed under the Clean Water Act
consists of those sources that introduce contaminants into a waterway
through overland or subsurface flow — these are called non-point sources,
and include most of the water pollution loads carried by urban stormwater
runoff.
Since the 1970s, the principal approach used by state and federal
environmental protection agencies to control water pollution is to try to
simply reduce the quantity of pollutants being released into our rivers and
streams (NRC, 2008). NPDES permits control the direct discharge of
contaminants into our waterways, while non-point sources are managed
through Best Management Practices (BMPs) that are designed to limit the
amount of pollutants released into a watershed, where they could later be
carried by stormwater runoff or by groundwater flow to a receiving stream
or river. Depending on the pollutant of concern, BMPs could be as simple
as requiring pet owners to clean up after their pets or as complex as
requiring that industries using toxic materials design, construct and manage
loading and storage areas in order to keep spilled materials from being
transported off-site by stormwater or groundwater flow. BMPs can even
include encouraging some industries to change their production processes in
order to reduce the total amount of toxic materials they use, a pollutant
reduction strategy known as pollution prevention (since the fewer toxics
used, the lower the risk that they will inadvertently be released into the
environment).
The strategy of simply reducing the amount of pollutants entering the
environment is complicated by the fact that many of the non-point
pollutants are not amenable to management through local BMPs. For
example, agricultural activities are expressly exempted from the Clean
Water Act, even though stormwater runoff from farms and animal feedlots
can carry agricultural chemicals, fertilizers and manure into adjacent
waterways, along with topsoil from freshly-plowed fields. Pollutants could
also be introduced into an urban watershed by the deposition of air
pollutants. Airborn particulate matter, for example, can be transported very
long distances by the wind, making most locally administered BMPs
(except possibly instituting regular street-sweeping programs) ineffective in
reducing the distribution and quantities of these types of urban stormwater
pollutants.
In response to these challenges, the Clean Water Act was amended to
require state environmental protection agencies to calculate pollution
budgets for the impaired segments of their streams and rivers. The
"impaired segments" were those reaches of a stream or river that did not
meet the water quality standards for their intended uses. Models were used
to calculate the "total maximum daily load" (TMDL) of pollutants entering
the waterway through both point and non-point sources that would enable
the stream segments to achieve their highest proposed use. The Clean Water
Act's new TMDL program provides a more sophisticated framework for
evaluating the impacts of non-point pollution on water quality. However,
given the limitations of trying to put more and better BMPs into place,
environmental protection agencies have begun to refocus some of their
attention from reducing the total amount of pollutants being released within
a watershed to also reducing the amount of stormwater runoff.
Environmental protection agencies have developed strategies for urban
stormwater management that involve modifying a development site so that
more precipitation would be retained on-site rather than flowing off of it
into nearby waterways or waterbodies. These stormwater retention
Strategies initially stressed traditional engineering solutions, such as
installing a stormwater collection system that temporarily stores the
stormwater on-site in order to reduce the rate and amount of stormwater
being released to a waterway. The strategies were later expanded to include
various site modifications, such as constructing vegetated buffer strips or
swales (ditches),in order to encourage more stormwater to infiltrate into the
ground.
Reducing the volume of urban stormwater leaving a site as runoff also
offers an additional hydrologic benefit in urban watersheds — reducing flood
risks (NRC 2008). Besides having the potential to carry pollutants,
stormwater runoff discharge increases the amount of water entering into a
lake, stream or river, increasing both the water volume and flow velocity of
the waterway. A relatively large amount of stormwater runoff entering a
waterway over a relatively short time can quickly raise a stream's water
levels beyond its banks, causing flooding that could threaten adjacent
development. Stormwater contribution to a river or stream can also increase
the velocity of the stream's flow, causing increased channel and bank
erosion, undercutting or damaging dikes, levees and other water control
structures, and scouring the stream or river bed. Stream edge or streambed
erosion can impair water quality by increasing the cloudiness (or turbidity)
of the waterway, which can also damage aquatic and riparian habitats.
Stormwater-induced flood risks are managed by the National Flood
Insurance Act, where hydrologic models (adjusted by historical flood
events) are used to forecast the potential flooding caused by a 100-year
storm (a storm that has a one percent chance of occurring in any given
year). The Act forces financial institutions to require homeowners within
the designated 100-year floodplains to purchase flood insurance in order to
get a mortgage, with the federal government subsidizing the insurance
premiums if the community adopts a flood management program restricting
development from extremely hazardous areas and instituting building code
changes to lessen flood damage.
In assessing flood risks, it is important to realize that managing the volume
and rate of urban stormwater being discharged from developed areas does
not affect the total amount of stormwater that is being discharged to a river
or stream within a watershed — they only affect the timing of when a storm's
precipitation will be discharged to the waterway (NRC, 2008). Both the
conventional and the newer, more sustainable, ways of managing
stormwater discussed below seek to delay the time it takes for stormwater
runoff to reach a waterway in order to reduce the water levels and flow
velocities of the receiving streams after a storm. Slowing the rate by which
stormwater is being contributed to a stream spreads out the peak of the
resultant flood levels over a longer time period, allowing many flood risks
to be substantially reduced.
Conventional Stormwater Management
Urban stormwater is traditionally managed by the construction of
engineered stormwater facilities, such as storm sewers and detention basins,
as part of the land development process. These engineering processes are
specifically designed to modify the natural hydrology of a site. For
example, when land is being developed, the parcel is usually graded for
development and stormwater infrastructure is installed to channel the
stormwater from individual lots into a separate stormwater sewer system
connected to a detention basin where it is retained until it can be discharged
off-site. Site preparation also includes elevating building sites so that they
are constructed on slightly elevated "pads" to encourage stormwater to flow
away from building foundations and toward the streets. After reaching the
street, stormwater is then directed to the stormwater sewers by curbs and
gutters.
Conventional stormwater detention facilities were historically built to
reduce off-site flood risks, and were not expressly designed to reduce off-
site water pollution risks. Any stormwater detention that was provided was
only temporary, often providing an insufficient retention time to allow the
natural attenuation of any pollutants that were carried by the runoff into the
detention basin — unlike the natural attenuation processes occurring in a
river or riparian wetland (where ambient pollution levels are gradually
reduced through dilution, oxidation, chemically binding to rocks and soils,
being gobbled up by microorganisms, etc.). Stormwater is usually detained
on-site after a storm only for a period of hours or, at most, days and then
released to a waterway. Some of the particulate contaminants in the stored
runoff might settle out if they are large or heavy enough to do so during that
short time, some might infiltrate into the soils in the bottom of the detention
basin, and some pollutants might be taken up by grass lining the basin, but
many pollutants still end up being carried into the waterway along with the
released stormwater.
Since the 1990s, environmental protection agencies have begun to consider
the water pollution impacts of releases from stormwater detention facilities,
after the Clean Water Act was amended to require states to treat stormwater
discharges from detention basins as a type of direct source and to require
that NPDES permits be phased in for discharges from Municipal Separate
Stormwater Sewer Systems ("MS4") in cities and urban areas above certain
population thresholds (NRC,_2008). The NPDES permits issued under the
U.S. Environmental Protection Agency's (U.S. EPA) MS4 program now
require the water pollution loads from stormwater detention basin
discharges to be assessed through the creation and adoption of local
stormwater management plans and that the contaminants carried by the
stormwater runoff to the basins for later re-release to a waterway be better
managed and reduced through the adoption of local BMPs. MS4 permit
regulations issued by state environmental protection agencies usually
involve the issuance of a "general permit" by the agency, applying to all
applicable Municipal Separate Stormwater Sewer Systems located within
the state’s designated urban areas.
Stormwater Sewer Systems Located within the State's Designated
Urban Areas
A different set of stormwater management issues arise in older urban areas
that are already developed. Most of the United States’ older cities and
suburbs, especially those established in the late-19"™ and early 20"
centuries, do not have Municipal Separate Stormwater Sewer Systems.
Instead, they have what are known as combined sewer systems — sewers
that carry both the stormwater runoff from paved streets and the wastewater
(sewage) from homes, stores and factories. These combined sewers
transport the mixed wastewater and stormwater to municipal sewage
treatment plants where the diluted sewage is treated and then discharged to
a waterway under an NPDES permit (NRC, 2008).
Water quality problems arise when rainstorms deposit more precipitation in
the city than can be handled by the sewage treatment plant. As the diluted
wastewater begins to fill up the combined sewer system at a faster rate than
it can be treated, the sewage treatment plant operators are faced with a
difficult choice — they can either allow the diluted sewage to continue to
back up in the sewers, eventually flooding residents' basements (a
politically unpopular as well as unhealthy option), or they can allow the
diluted wastewater to bypass the sewage treatment plant and be discharged
directly into the waterway, with the untreated wastewater's pollutant levels
usually exceeding the limits set forth in the plant's NPDES permit. Most
treatment plant operators choose the more politically acceptable option of
releasing the wastewater in violation of their NPDES permit, creating water
pollution incidents called combined sewer overflows (CSQs).
Strategies to Manage CSOs
CSO problems are very difficult and expensive to resolve in older cities.
One approach to managing stormwater off-site is to tear up the city's streets,
digging up the old combined sewers and replacing them with separate
stormwater and wastewater sewer systems. The high costs of retrofitting
new separate sewer systems are often prohibitively expensive, especially in
these times of stressed state and local budgets. Moreover, the extensive
traffic disruptions involved in replacing most streets would not make this a
politically popular choice.
A second approach to managing CSO issues off-site in developed areas is to
keep the combined sewer system, but to construct a reservoir system large
enough to store the diluted wastewater until it can be treated by the sewage
treatment plant. This is the approach used by both the City of Milwaukee,
Wisconsin and by the Metropolitan Water Reclamation District of Greater
Chicago in its Tunnel and Reservoir Plan, or TARP. Although most of
TARP has been built, all of the reservoirs have not yet been completed
because of federal budgetary cutbacks. The tunnels themselves and one
reservoir are currently able to temporarily store the combined sewage and
the runoff from only the first 3/8-inch (.95 cm) of rain falling in the
Metropolitan Water Reclamation District's service area. The extremely high
expense of installing such a supplementary sewage and stormwater storage
system would make it unaffordable to most cities unless very substantial
federal and state grants are provided.
A third way to address CSO issues off-site is to use the streets themselves to
temporarily store stormwater by installing low speed bump-like structures
at intersections and by restricting the streets' sewer intakes to the combined
sewer system (US EPA, 2000). This urban retrofit strategy would allow
stormwater to flow from lots into the streets, which would flood up to their
gutter tops during heavy storms, functioning as stormwater reservoirs. The
stored stormwater would then slowly be discharged to the combined sewers
through the restricted grates over a period of hours after the storm, reducing
the amount of diluted sewage flow to a quantity that could be adequately
treated by sewage treatment plants. The flooding of streets, impairing
automobile access, and the possibility of stormwater overflowing the curbs
and damaging parked cars and adjacent property during very heavy
rainstorms may not make this a politically popular option, though.
Managing Urban Stormwater More Sustainably
There is a fourth approach to dealing with CSO problems, which involves
intercepting and delaying the discharge of precipitation from a parcel of
land before it flows off-site to a separate or combined sewer system, or to
an adjacent waterway. Encouraging on-site storage or infiltration reduces
the stormwater contribution to a combined sewer's flow in developed areas,
thereby reducing the amount of diluted wastewater being generated and
enabling combined sewer systems to better handle their wastewater loads
during rainstorms. These decentralized on-site approaches to managing
stormwater could also be used to reduce the amount of conventional
stormwater infrastructure needed in new developments using separate
stormwater sewer systems. Because these on-site approaches are less
resource-intensive and more cost-effective than conventional stormwater
management approaches, they are also more sustainable investments.
On-site stormwater management techniques are also often known as "green
infrastructure" (Jaffe et al., 2010). Development projects using "green
infrastructure" for urban stormwater management are commonly known as
"Low Impact Developments." Low Impact Development projects using
green infrastructure usually allow stormwater to be managed at lower costs
than by using conventional detention practices (US EPA, 2007).
There are essentially three strategies for on-site stormwater management:
(1) techniques that encourage the infiltration of stormwater into soils to
reduce its volume before it reaches a sewer system, or which employ more
selective grading and the planting of vegetation to reduce its rate of flow
from the site; (2) techniques that encourage the temporary storage of
stormwater on-site, instead of transporting it off-site for centralized
detention within a development project or a municipality; and (3)
techniques, such as the construction of artificial wetlands, which also allow
some degree of longer-term retention and treatment of the stormwater by
natural processes before it is discharged. Infiltration techniques might also
provide some water treatment capabilities due to the longer retention times
of groundwater before discharge, but the degree of such treatment would
largely depend on soil characteristics, the amount of overlying vegetation
and the depth of the soil's unsaturated zone.
Increasing Stormwater Infiltration
Techniques to decrease the volume of stormwater runoff and to reduce the
rates at which it is discharged include the use of permeable paving and the
construction of "rain gardens" and vegetated swales (see Figure Permeable
Paving & Vegetated Swales). Permeable paving uses materials which are
specially formulated to have air voids in their matrix, allowing water to
flow into and through the paving materials after they are installed. It also
includes the more common installation of precast porous pavers that are
designed with holes through their surfaces, allowing stormwater to flow
through their holes into the soils beneath them. Permeable paving needs to
be periodically maintained because its pores can be clogged by fine grains
of topsoil or with other small particles (such as soot from atmospheric
deposition) carried along by the runoff. Maintenance includes periodically
Sweeping or vacuuming the paving to control the build-up of clogging
particles.
Permeable Paving & Vegetated Swales Permeable paving
drains into a vegetated swale as part of Elmhurst College's
(in Illinois) parking lot's "green" stormwater management
"Rain gardens" can also be used to encourage stormwater to infiltrate into
the soils, where it can be taken up by plants and transpired to the
atmosphere, evaporated from the soils, or allowed to infiltrate deeper into
the soils to become groundwater. Rain gardens are created in areas of low-
lying terrain that are expressly designed for, or engineered with, well-
drained soils and are usually planted with deep-rooted native vegetation
that often can survive the drier soil conditions between rains. Rain gardens
can be quite effective in intercepting and infiltrating stormwater being
discharged from roofs, with roof downspouts directing the discharge of
stormwater into a rain garden instead of allowing it to flow across the lot
and into the street sewer system. Some native vegetation, however, may
have special maintenance requirements, such as the periodic burning
needed to manage some prairie plants.
Vegetated ditches or swales can also be used to transport stormwater runoff
to a conventional stormwater management system, with the vegetation
planted in the ditch slowing the rate of stormwater flow while also allowing
a portion of the runoff to be infiltrated into the soils or taken up by plants.
In many cases, vegetated swales and rain gardens can provide less-
expensive alternatives to the installation of separate stormwater sewer
system, since it reduces the need for the construction of street gutters,
grates, street catchment basins and sewer pipes (US EPA, 2007).
Interception of the stormwater by infiltration and plant uptake in a rain
garden or vegetated swale may also reduce the amount, capacity and size of
the sewers that would have to be built to manage a predicted volume of
stormwater, if these green infrastructure techniques are used to supplement
a conventional stormwater collection system.
Increasing Interim On-site Storage
Sustainable management techniques that can temporarily store stormwater
on-site until it can be released off-site to a sewer system or to conventional
stormwater detention facilities include the use of "green roofs" and rain
barrels connected to roof downspouts. Rain barrels allow precipitation to
be collected and stored, and then used for non-potable purposes (lawn
irrigation, for instance) allowing the captured stormwater to substitute for
more expensive, treated water (see Figure A Rain Barrel Collection
System).
A Rain Barrel Collection System This "green" building
(Ryerson Woods Welcome Center, Lake County (Illinois)
Forest Preserve District )uses both a rain barrel to collect
stormwater draining from the roof, and a rain garden to help
12, p. 116.
A green roof is a flat roof surface that uses amended soil materials installed
above a layer of waterproof roofing materials to allow shallow-rooted
plants to be planted. While still being an impermeable feature of a
development site (because of its waterproof layer), a green roof can
temporarily store rainwater before it is discharged to the ground by the roof
gutters and downspouts (see Figure A Green Roof). Just as a rain barrel can
store (and re-use) a portion of the stormwater precipitation being discharged
from impervious roofs, the soils of a green roof can capture and temporarily
store stormwater precipitation as the pores between the soil particles fill up
with rainwater. Green roofs can even partially reduce the runoff's pollution
load through plant uptake and by other biological and physical processes
within the roofs' soil materials while they are saturated. Because of the need
to both water-proof the roof while installing a biological system on top of it,
green roofs tend to cost more than conventional roofs, even ignoring the
additional structural engineering that might be necessary to accommodate
the weight of the green roof's soil and plantings.
A Green Roof The green roof on this police
station in Village of Villa Park, Illinois has
shallow-rooted plants placed in a thin layer of
growing medium installed on top of a waterproof
Fig. 13, p. 116.
The stormwater management benefits of rain barrels and green roofs
depend on their storage capacity relative to the amount of impervious
surface area of the roof with which they are associated. Rain barrels might
be able to capture only a fraction of an inch of the stormwater falling on a
roof and being discharged from a downspout, while several inches of
amended soils on a rooftop might be able to store substantially more
precipitation before it evaporates, is taken up by the roof's plants, or is
discharged from the green roof via its gutters and downspouts. In both
cases, however, the interception and temporary retention of stormwater by
these green technologies may allow conventional stormwater management
systems to function more efficiently by reducing the amount of stormwater
being discharged into the systems. They would also certainly reduce some
of the "peakiness" of stream flooding by being able to temporarily store
and then release stormwater from impermeable roof surfaces later after a
storm event.
Treating Urban Stormwater
Some sustainable stormwater management approaches have the potential to
actually treat the water to remove pollutants as well as control its volume
and rate of discharge. These strategies include constructing wetlands and
planting trees. Wetlands have proven to be very effective in both
temporarily storing stormwater runoff and reducing flooding risks, while
also reducing the pollutant load carried to the wetland (because of its high
biological activity that can capture and degrade the contaminants). As a
result, the federal government has adopted a "no net loss" policy with
respect to protecting existing wetlands. Section 404 of the federal Clean
Water Act requires that the U.S. Army Corps of Engineers (under U.S. EPA
oversight) review any proposals to fill or damage any wetlands that are
directly hydrologically associated with navigable waterways. Any actions
affecting existing wetlands will need a Corps 404 permit in addition to any
local or state approvals.
Besides preserving existing wetlands, new wetlands can also be designed,
created and maintained as part of a "green" stormwater management
strategy (NRC, 2008). The constructed wetland can be designed and used to
intercept, temporarily store and treat stormwater runoff before it is released
to a stream or river. Water control structures are also usually installed to
ensure that the constructed wetlands remain flooded for long enough
periods of time to support wetland vegetation. If appropriate plants are
selected, they can also provide important habitats. Wetland maintenance
involves the control of invasive plant species (e.g. Purple Loosestrife) and
the management of any sediment that can be carried by stormwater runoff
into the wetland, since the sedimentation of wetlands can fill them in,
impairing their ecological and treatment functions.
The planting of trees is an especially valuable strategy to manage urban
stormwater, especially when the trees become mature. Tree canopies break
rain velocity, reducing runoff flow rates, while tree roots can stabilize soils
against being eroded by urban runoff. Tree canopies reduce temperatures,
mitigating urban heat island effects, by providing shade and through their
transpiration processes. Their leaves and roots can also capture some
stormwater contaminants and provide carbon sequestration to reduce
climate change impacts. Moreover, trees provide a valuable soil amendment
as their fallen leaves decay into mulch, improving the infiltration rate and
biological activity of surrounding soils, while larger broken branches falling
into urban streams can slow stream velocities and provide improved
riparian and aquatic habitat. The shading of streams by riparian trees is
particularly important in ensuring that a stream's ecological functions
remain resilient in the face of rising temperatures caused by global climate
change.
Conclusions
All of the green infrastructure and Low Impact Development techniques
that provide interim on-site stormwater storage to reduce flood risks can
also provide some pollution removal capabilities, as well. The American
Society of Civil Engineers and U.S. EPA maintain an International
Stormwater BMP Database of development projects using green
infrastructure. This on-line resource reviews the effectiveness of various
stormwater management practices and makes these sustainable techniques
more accessible to local officials and municipal public works departments
charged with managing stormwater runoff in their communities.
There is increasing public interest in using sustainable stormwater
management techniques to replace or supplement conventional stormwater
facilities. The U.S. federal government, for example, is now requiring that
green infrastructure be used in all federal projects above a certain size to
manage urban stormwater runoff. Local officials are also showing a greater
interest in these sustainable approaches, since they are often less expensive
to install and maintain over their life-spans than conventional stormwater
sewer systems and detention facilities. Finally, state governments are
beginning to set aside money in their revolving loan funds for public
infrastructure that is earmarked for green infrastructure projects. It is likely
that this interest in sustainable urban stormwater management will continue
to grow.
Review Questions
Exercise:
Problem:
Which of the sustainable urban stormwater management practices can
best be used in existing neighborhoods, and which are best suited for
new development?
Exercise:
Problem:
The performance of many of the green infrastructure practices often
depends on how well they are maintained over their life-spans. What
are some effective strategies that local officials can consider in order to
ensure that the green infrastructure being used to manage urban
stormwater in their communities is adequately maintained and
continues to perform as designed?
Resources
For more information about the:
e Clean Water Act, visit http://www.epa.gov/agriculture/Icwa.html.
e International Stormwater BMP Database, visit
http://www.bmpdatabase.org.
e Metropolitan Water Reclamation District of Greater Chicago, visit
e Milwaukee Metropolitan Sewerage District, visit
http://v3.mmsd.com/DeepTunnel.aspx.
e National Flood Insurance Act, visit
http://www.fema.gov/library/viewRecord.do?id=2216.
References
Gulliver, G.S. & Anderson, J.L. (eds.). (2008). Assessment of Stormwater
Best Management Practices. Stormwater Management Practice Assessment
Study. Minneapolis: University of Minnesota.
Jaffe, M., Zellner, M., Minor, E., Gonzalez-Meler, M., Cotner, L., Massey,
D., Ahmed, H., Elbert M., Wise, S., Sprague, H., & Miller, B. (2010). Using
Green Infrastructure to Manage Urban Stormwater Quality: A Review of
Selected Practices and State Programs. Springfield, IL: Illinois
Environmental Protection Agency. Retrieved June 23, 2011 from
recommendations.pdf
National Research Council. (2008). Urban Stormwater Management in the
United States. Washington, DC: National Academies Press. Retrieved June
U.S. Environmental Protection Agency. (2000, October). Street Storage for
Combined Sewer Surcharge Control: Skokie and Wilmette, Illinois
(Factsheet). (EPA Publication No. EPA-841-B-00-005C). Washington, D.C.
Retrieved May 17, 2011 from
http://www.lowimpactdevelopment.org/pubs/Street_ Storage Factsheet.pdf
U.S. Environmental Protection Agency. (2007, December). Reducing
Stormwater Costs through Low Impact Development (LID) Strategies and
Practices. (EPA Publication No. EPA 841-F-07-006). Washington. D.C.
Retrieved June 23, 2011 from
http://www.epa.gov/owow/NPS/lid/costs07/documents/reducingstormwater
costs.pdf
U.S. Global Climate Change Research Program (USGCCRP). 2009. Global
Climate Change Impacts in the United States. Cambridge: Cambridge
University Press. Retrieved May 18, 2011 from
http://downloads.globalchange. gov/usimpacts/pdfs/climate-impacts-
report.pdf
Glossary
ambient water quality
The concentration of pollutants found within waterbodies and
waterways.
combined sewer overflows (CSOs)
The overflow and discharge of excess wastewater to surface waters
during storms, when diluted wastewater flows exceed the capacity of a
combined sewer systems or sewage treatment plant.
combined sewer systems
Sewer systems that are designed to collect stormwater runoff and
domestic and industrial wastewater within the same sewer pipes.
"first flush" phenomenon
The higher pollutant concentrations found at the beginning of a storm
or spring snowmelt.
green roof
Vegetation and planting media installed on a rooftop in order to store
and delay stormwater runoff from the roof's surface.
hydrology
The scientific examination of the occurrence, distribution, movement
and properties of water within the natural environment.
low impact development
An approach to land development (or re-development) that uses
natural drainage and environmental processes to manage stormwater as
close to its source as possible.
Native vegetation
"Wild" plants that have naturally evolved and successfully adapted to a
region's environmental conditions.
non-point source
The term "nonpoint source" is defined to mean any source of water
pollution that does not meet the legal definition of "point source" in
section 502(14) of the Clean Water Act (see "Point Source" definition
below)
"peaky" waterways
The "peakiness" of a waterway describes the more rapid increase and
decline in stream flow and the higher stream levels after a storm in
urbanized watersheds compared to the more gradual rise and decline in
stream volumes and lower water levels in less-developed drainage
basins after the same storm event, largely because of the greater
amounts of impervious surfaces and runoff generated within urban
areas.
point source
Defined by Section 502(14) of the Clean Water Act as any single
identifiable and discrete source of pollution from which pollutants are
discharged, such as from a pipe, ditch, channel, culvert, confined
animal feeding operation, or discharged from a floating vessel.
pollution prevention
Reducing or eliminating waste at the source by modifying production
processes, promoting the use of non-toxic or less-toxic substances,
implementing conservation techniques, and re-using materials rather
than putting them into the waste stream.
rain barrel
A cistern, barrel or storage system that collects and stores the
rainwater or snowmelt from roofs that would otherwise be diverted to
storm drains and streams as stormwater runoff.
stormwater runoff
The overland flow of precipitation generated by that portion of rain
and snowmelt that does not infiltrate into the ground, is not taken up
by plants, and is not evaporated into the atmosphere.
Swales
Graded and engineered landscape features designed as vegetated,
shallow, open channels or ditches that are usually planted with flood
tolerant and erosion resistant plants.
watershed
A geographic area that naturally drains to a specific waterway or
waterbody.
Case Study: A Net-Zero Energy Home in Urbana, Illinois
How much fossil fuel does it take to operate a comfortable home for a
couple of retired American baby-boomers?
None.
That’s according to Ty and Deb Newell of Urbana, Illinois. Moreover, they
hope the example of their home, the Equinox House, will awaken others to
the opportunity of constructing a net-zero energy house in the Midwest
using technology available today.
The Equinox House The picture of the house on a sunny November
day shows the passive solar entering the clerestory windows. Source:
© 2012 Equinox Built Environment Engineering;_a division of Newell
Instruments Inc.
The Newells celebrated the first anniversary of life in the Equinox House in
late 2011, so they now possess more than a year’s worth of data about how
much electricity they used on day-to-day basis, as well as how much
electricity their solar panels produced.
According to Ty Newell, who is professor emeritus of mechanical
engineering at the University of Illinois at Urbana-Champaign, the Equinox
House required about 12,000 kilowatt-hours of electricity to operate from
December 2010 through November 2011. That total includes electricity for
heating and air conditioning, hot water heat, clothes washing and drying,
and all other appliances. No natural gas is used in the house.
Newell noted that energy use in the Equinox House for the first year was
approximately 20 percent greater than it will be in 2012 and subsequent
years. That’s because he was using the least efficient of three different
heating systems that will be tested in the home.
During the first year, the solar panels that power the Equinox House
produced approximately 11,000 kilowatt-hours of electricity. This would
have made the Newells purchasers of 1,000 kilowatt-hours, in net terms,
had it not been for the fact that the solar panels were on line for some time
before they moved into the house.
Thanks to the more efficient heating system now in place, the Equinox
House will produce surplus electricity in 2012 and in the future. That’s by
design. The surplus will be used to power their all-electric Ford Focus for
the 8,000 miles of in-town driving they do annually.
In conjunction with its solar panels, the Equinox House achieves net-zero
energy use because it requires far less energy than even a well-built
conventional home—about one-fifth as much. It does so through the use of
design and technology that did not add a significant burden to the cost of
construction.
The walls and roof of the Equinox House are constructed with twelve-inch
thick structural insulated panels, which are four to five times more effective
at preventing thermal transfer than the walls of a typical house. Great care
has also been taken to minimize any leakage of air through envelope of the
house.
The Equinox House uses high performance, triple-pane windows, which
also help to prevent thermal transfer. Beyond that, the windows are oriented
to allow direct sunlight into living space for the heat it provides during the
cooler half of the year—beginning on the Fall equinox—and to exclude
direct sunlight during the warmer half of the year—beginning on the Spring
equinox—when it would increase the load on the cooling system.
Ultimately, the demands of the Equinox House for heating, cooling,
ventilation, and humidity control will all be met by a single, heat-pump
based system, developed by Ty Newell and his son Ben through their
company, Newell Instruments. Aside from the fact that it maintains a
comfortable temperature and level of humidity in the house, this system
also delivers a constant flow of fresh air from the outside, and it does that
without the loss of conditioned air that occurs in a drafty house.
Of course the Equinox House will be outfitted in other ways that emphasize
conservation, including LED lighting, low-flow plumbing fixtures, etc. It
even features a system for collecting rainwater that is designed to meet 80
percent of the annual water needs for a family of four.
When he talks about the Equinox House, Ty Newell emphasizes how well it
works from an economic perspective, since the couple’s average daily cost
for energy is a mere $3.00. That’s based on a twenty-year life for the solar
array, which cost a net of $20,000 installed.
In addition, Newell enjoys the fact that a significant part of their up-front
expenditure supported job creation, the labor that went into the manufacture
and installation of their solar panels. That’s in contrast to money they might
have otherwise spent on fossil fuel.
You might think that the Newells must be sacrificing comfort for the sake of
energy savings, but that’s not the case. Their house boasts 2,100 square feet
of living space and all of the amenities you would expect in a contemporary
suburban residence.
On top of that, they enjoy much better indoor air quality than people who
live in conventional homes, thanks to a constant flow of conditioned fresh
air from the outside.
You can find photos and further information about the Equinox House and
net-zero living at http://newellinstruments.com/equinox
Live Music
Archive
Librivox
Free Audio
Metropolitan Museum
Cleveland
Museum of Art
Internet
Arcade
Console Living Room
Open Library
American
Libraries
TV News
Understanding
9/11